Auto merge of #5480 - SimonSapin:multicol, r=pcwalton

This add some properties to the style system and a new flow type, but the larger issues of dealing with fragmentation in the flow tree is still an open question.

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15 files changed, 388 insertions, 125 deletions

diff --git a/components/layout/block.rs b/components/layout/block.rs
index 4c50adb3e6a..c21d3123bc7 100644
--- a/components/layout/block.rs
+++ b/components/layout/block.rs
@@ -562,33 +562,20 @@ impl Encodable for BlockFlowFlags {
 }
 
 impl BlockFlow {
-    pub fn from_node_and_fragment(node: &ThreadSafeLayoutNode, fragment: Fragment) -> BlockFlow {
+    pub fn from_node_and_fragment(node: &ThreadSafeLayoutNode,
+                                  fragment: Fragment,
+                                  float_kind: Option<FloatKind>)
+                                  -> BlockFlow {
         let writing_mode = node.style().writing_mode;
         BlockFlow {
-            base: BaseFlow::new(Some((*node).clone()),
-                                writing_mode,
-                                ForceNonfloatedFlag::ForceNonfloated),
+            base: BaseFlow::new(Some((*node).clone()), writing_mode, match float_kind {
+                Some(_) => ForceNonfloatedFlag::FloatIfNecessary,
+                None => ForceNonfloatedFlag::ForceNonfloated,
+            }),
             fragment: fragment,
             inline_size_of_preceding_left_floats: Au(0),
             inline_size_of_preceding_right_floats: Au(0),
-            float: None,
-            flags: BlockFlowFlags::empty(),
-        }
-    }
-
-    pub fn float_from_node_and_fragment(node: &ThreadSafeLayoutNode,
-                                        fragment: Fragment,
-                                        float_kind: FloatKind)
-                                        -> BlockFlow {
-        let writing_mode = node.style().writing_mode;
-        BlockFlow {
-            base: BaseFlow::new(Some((*node).clone()),
-                                writing_mode,
-                                ForceNonfloatedFlag::FloatIfNecessary),
-            fragment: fragment,
-            inline_size_of_preceding_left_floats: Au(0),
-            inline_size_of_preceding_right_floats: Au(0),
-            float: Some(box FloatedBlockInfo::new(float_kind)),
+            float: float_kind.map(|kind| box FloatedBlockInfo::new(kind)),
             flags: BlockFlowFlags::empty(),
         }
     }
@@ -1379,7 +1366,8 @@ impl BlockFlow {
                 FormattingContextType::Other
             }
             _ if style.get_box().overflow_x != overflow_x::T::visible ||
-                    style.get_box().overflow_y != overflow_y::T(overflow_x::T::visible) => {
+                    style.get_box().overflow_y != overflow_y::T(overflow_x::T::visible) ||
+                    style.is_multicol() => {
                 FormattingContextType::Block
             }
             _ => FormattingContextType::None,
diff --git a/components/layout/construct.rs b/components/layout/construct.rs
index f945e8bb526..6c4537e8b26 100644
--- a/components/layout/construct.rs
+++ b/components/layout/construct.rs
@@ -33,6 +33,7 @@ use fragment::{InlineBlockFragmentInfo, SpecificFragmentInfo};
 use incremental::{RECONSTRUCT_FLOW, RestyleDamage};
 use inline::InlineFlow;
 use list_item::{ListItemFlow, ListStyleTypeContent};
+use multicol::MulticolFlow;
 use opaque_node::OpaqueNodeMethods;
 use parallel;
 use table::TableFlow;
@@ -330,7 +331,7 @@ impl<'a> FlowConstructor<'a> {
         if child.is_table() {
             let fragment = Fragment::new(child_node, SpecificFragmentInfo::TableWrapper);
             let mut new_child =
-                FlowRef::new(box TableWrapperFlow::from_node_and_fragment(child_node, fragment));
+                FlowRef::new(box TableWrapperFlow::from_node_and_fragment(child_node, fragment, None));
             new_child.add_new_child(child.clone());
             child.finish();
             *child = new_child
@@ -601,7 +602,7 @@ impl<'a> FlowConstructor<'a> {
     ///
     /// FIXME(pcwalton): It is not clear to me that there isn't a cleaner way to handle
     /// `<textarea>`.
-    fn build_flow_for_block(&mut self, flow: FlowRef, node: &ThreadSafeLayoutNode)
+    fn build_flow_for_block_like(&mut self, flow: FlowRef, node: &ThreadSafeLayoutNode)
                             -> ConstructionResult {
         let mut initial_fragments = LinkedList::new();
         if node.get_pseudo_element_type() != PseudoElementType::Normal ||
@@ -653,21 +654,15 @@ impl<'a> FlowConstructor<'a> {
     /// Builds a flow for a node with `display: block`. This yields a `BlockFlow` with possibly
     /// other `BlockFlow`s or `InlineFlow`s underneath it, depending on whether {ib} splits needed
     /// to happen.
-    fn build_flow_for_nonfloated_block(&mut self, node: &ThreadSafeLayoutNode)
-                                       -> ConstructionResult {
-        let flow = box BlockFlow::from_node_and_fragment(node, self.build_fragment_for_block(node))
-            as Box<Flow>;
-        self.build_flow_for_block(FlowRef::new(flow), node)
-    }
-
-    /// Builds the flow for a node with `float: {left|right}`. This yields a float `BlockFlow` with
-    /// a `BlockFlow` underneath it.
-    fn build_flow_for_floated_block(&mut self, node: &ThreadSafeLayoutNode, float_kind: FloatKind)
-                                    -> ConstructionResult {
+    fn build_flow_for_block(&mut self, node: &ThreadSafeLayoutNode, float_kind: Option<FloatKind>)
+                            -> ConstructionResult {
         let fragment = self.build_fragment_for_block(node);
-        let flow = box BlockFlow::float_from_node_and_fragment(node, fragment, float_kind) as
-            Box<Flow>;
-        self.build_flow_for_block(FlowRef::new(flow), node)
+        let flow = if node.style().is_multicol() {
+            box MulticolFlow::from_node_and_fragment(node, fragment, float_kind) as Box<Flow>
+        } else {
+            box BlockFlow::from_node_and_fragment(node, fragment, float_kind) as Box<Flow>
+        };
+        self.build_flow_for_block_like(FlowRef::new(flow), node)
     }
 
     /// Concatenates the fragments of kids, adding in our own borders/padding/margins if necessary.
@@ -814,7 +809,7 @@ impl<'a> FlowConstructor<'a> {
 
     fn build_fragment_for_inline_block(&mut self, node: &ThreadSafeLayoutNode)
                                        -> ConstructionResult {
-        let block_flow_result = self.build_flow_for_nonfloated_block(node);
+        let block_flow_result = self.build_flow_for_block(node, None);
         let (block_flow, abs_descendants) = match block_flow_result {
             ConstructionResult::Flow(block_flow, abs_descendants) => (block_flow, abs_descendants),
             _ => unreachable!()
@@ -840,7 +835,7 @@ impl<'a> FlowConstructor<'a> {
     /// hypothetical box is inline.
     fn build_fragment_for_absolutely_positioned_inline(&mut self, node: &ThreadSafeLayoutNode)
                                                        -> ConstructionResult {
-        let block_flow_result = self.build_flow_for_nonfloated_block(node);
+        let block_flow_result = self.build_flow_for_block(node, None);
         let (block_flow, abs_descendants) = match block_flow_result {
             ConstructionResult::Flow(block_flow, abs_descendants) => (block_flow, abs_descendants),
             _ => unreachable!()
@@ -934,13 +929,8 @@ impl<'a> FlowConstructor<'a> {
     fn build_flow_for_table_wrapper(&mut self, node: &ThreadSafeLayoutNode, float_value: float::T)
                                     -> ConstructionResult {
         let fragment = Fragment::new(node, SpecificFragmentInfo::TableWrapper);
-        let wrapper_flow = match float_value {
-            float::T::none => box TableWrapperFlow::from_node_and_fragment(node, fragment),
-            _ => {
-                let float_kind = FloatKind::from_property(float_value);
-                box TableWrapperFlow::float_from_node_and_fragment(node, fragment, float_kind)
-            }
-        };
+        let wrapper_flow = box TableWrapperFlow::from_node_and_fragment(
+            node, fragment, FloatKind::from_property(float_value));
         let mut wrapper_flow = FlowRef::new(wrapper_flow as Box<Flow>);
 
         let table_fragment = Fragment::new(node, SpecificFragmentInfo::Table);
@@ -948,7 +938,7 @@ impl<'a> FlowConstructor<'a> {
         let table_flow = FlowRef::new(table_flow as Box<Flow>);
 
         // First populate the table flow with its children.
-        let construction_result = self.build_flow_for_block(table_flow, node);
+        let construction_result = self.build_flow_for_block_like(table_flow, node);
 
         let mut abs_descendants = Descendants::new();
         let mut fixed_descendants = Descendants::new();
@@ -1003,7 +993,7 @@ impl<'a> FlowConstructor<'a> {
     fn build_flow_for_table_caption(&mut self, node: &ThreadSafeLayoutNode) -> ConstructionResult {
         let fragment = self.build_fragment_for_block(node);
         let flow = box TableCaptionFlow::from_node_and_fragment(node, fragment) as Box<Flow>;
-        self.build_flow_for_block(FlowRef::new(flow), node)
+        self.build_flow_for_block_like(FlowRef::new(flow), node)
     }
 
     /// Builds a flow for a node with `display: table-row-group`. This yields a `TableRowGroupFlow`
@@ -1013,7 +1003,7 @@ impl<'a> FlowConstructor<'a> {
         let fragment = Fragment::new(node, SpecificFragmentInfo::TableRow);
         let flow = box TableRowGroupFlow::from_node_and_fragment(node, fragment);
         let flow = flow as Box<Flow>;
-        self.build_flow_for_block(FlowRef::new(flow), node)
+        self.build_flow_for_block_like(FlowRef::new(flow), node)
     }
 
     /// Builds a flow for a node with `display: table-row`. This yields a `TableRowFlow` with
@@ -1021,7 +1011,7 @@ impl<'a> FlowConstructor<'a> {
     fn build_flow_for_table_row(&mut self, node: &ThreadSafeLayoutNode) -> ConstructionResult {
         let fragment = Fragment::new(node, SpecificFragmentInfo::TableRow);
         let flow = box TableRowFlow::from_node_and_fragment(node, fragment) as Box<Flow>;
-        self.build_flow_for_block(FlowRef::new(flow), node)
+        self.build_flow_for_block_like(FlowRef::new(flow), node)
     }
 
     /// Builds a flow for a node with `display: table-cell`. This yields a `TableCellFlow` with
@@ -1042,17 +1032,14 @@ impl<'a> FlowConstructor<'a> {
 
         let flow = box TableCellFlow::from_node_fragment_and_visibility_flag(node, fragment, !hide)
             as Box<Flow>;
-        self.build_flow_for_block(FlowRef::new(flow), node)
+        self.build_flow_for_block_like(FlowRef::new(flow), node)
     }
 
     /// Builds a flow for a node with `display: list-item`. This yields a `ListItemFlow` with
     /// possibly other `BlockFlow`s or `InlineFlow`s underneath it.
     fn build_flow_for_list_item(&mut self, node: &ThreadSafeLayoutNode, flotation: float::T)
                                 -> ConstructionResult {
-        let flotation = match flotation {
-            float::T::none => None,
-            flotation => Some(FloatKind::from_property(flotation)),
-        };
+        let flotation = FloatKind::from_property(flotation);
         let marker_fragment = match node.style().get_list().list_style_image {
             Some(ref url) => {
                 let image_info = box ImageFragmentInfo::new(node,
@@ -1289,7 +1276,7 @@ impl<'a> PostorderNodeMutTraversal for FlowConstructor<'a> {
             // below.
             (display::T::block, _, position::T::absolute) |
             (_, _, position::T::fixed) => {
-                let construction_result = self.build_flow_for_nonfloated_block(node);
+                let construction_result = self.build_flow_for_block(node, None);
                 self.set_flow_construction_result(node, construction_result)
             }
 
@@ -1364,15 +1351,9 @@ impl<'a> PostorderNodeMutTraversal for FlowConstructor<'a> {
             // TODO(pcwalton): Make this only trigger for blocks and handle the other `display`
             // properties separately.
 
-            (_, float::T::none, _) => {
-                let construction_result = self.build_flow_for_nonfloated_block(node);
-                self.set_flow_construction_result(node, construction_result)
-            }
-
-            // Floated flows contribute float flow construction results.
             (_, float_value, _) => {
                 let float_kind = FloatKind::from_property(float_value);
-                let construction_result = self.build_flow_for_floated_block(node, float_kind);
+                let construction_result = self.build_flow_for_block(node, float_kind);
                 self.set_flow_construction_result(node, construction_result)
             }
         }
diff --git a/components/layout/floats.rs b/components/layout/floats.rs
index 5f61760829b..a3f06e80667 100644
--- a/components/layout/floats.rs
+++ b/components/layout/floats.rs
@@ -19,11 +19,11 @@ pub enum FloatKind {
 }
 
 impl FloatKind {
-    pub fn from_property(property: float::T) -> FloatKind {
+    pub fn from_property(property: float::T) -> Option<FloatKind> {
         match property {
-            float::T::none => panic!("can't create a float type from an unfloated property"),
-            float::T::left => FloatKind::Left,
-            float::T::right => FloatKind::Right,
+            float::T::none => None,
+            float::T::left => Some(FloatKind::Left),
+            float::T::right => Some(FloatKind::Right),
         }
     }
 }
diff --git a/components/layout/flow.rs b/components/layout/flow.rs
index 5434676ad03..a745ca8010b 100644
--- a/components/layout/flow.rs
+++ b/components/layout/flow.rs
@@ -44,6 +44,7 @@ use table_colgroup::TableColGroupFlow;
 use table_row::TableRowFlow;
 use table_rowgroup::TableRowGroupFlow;
 use table_wrapper::TableWrapperFlow;
+use multicol::MulticolFlow;
 use wrapper::ThreadSafeLayoutNode;
 
 use geom::{Point2D, Rect, Size2D};
@@ -158,6 +159,11 @@ pub trait Flow: fmt::Debug + Sync {
         panic!("called as_table_cell() on a non-tablecell flow")
     }
 
+    /// If this is a multicol flow, returns the underlying object. Fails otherwise.
+    fn as_multicol<'a>(&'a mut self) -> &'a mut MulticolFlow {
+        panic!("called as_multicol() on a non-multicol flow")
+    }
+
     /// If this is a table cell flow, returns the underlying object, borrowed immutably. Fails
     /// otherwise.
     fn as_immutable_table_cell<'a>(&'a self) -> &'a TableCellFlow {
@@ -451,6 +457,7 @@ pub enum FlowClass {
     TableRow,
     TableCaption,
     TableCell,
+    Multicol,
 }
 
 /// A top-down traversal.
diff --git a/components/layout/lib.rs b/components/layout/lib.rs
index 7fbbb2d3576..844689f0534 100644
--- a/components/layout/lib.rs
+++ b/components/layout/lib.rs
@@ -78,6 +78,7 @@ pub mod incremental;
 pub mod inline;
 pub mod list_item;
 pub mod model;
+pub mod multicol;
 pub mod opaque_node;
 pub mod parallel;
 pub mod sequential;
diff --git a/components/layout/list_item.rs b/components/layout/list_item.rs
index cec7b02f0a5..8bf3fee6880 100644
--- a/components/layout/list_item.rs
+++ b/components/layout/list_item.rs
@@ -45,11 +45,7 @@ impl ListItemFlow {
                                              flotation: Option<FloatKind>)
                                              -> ListItemFlow {
         let mut this = ListItemFlow {
-            block_flow: if let Some(flotation) = flotation {
-                BlockFlow::float_from_node_and_fragment(node, main_fragment, flotation)
-            } else {
-                BlockFlow::from_node_and_fragment(node, main_fragment)
-            },
+            block_flow: BlockFlow::from_node_and_fragment(node, main_fragment, flotation),
             marker: marker_fragment,
         };
 
diff --git a/components/layout/multicol.rs b/components/layout/multicol.rs
new file mode 100644
index 00000000000..e46ea8abf71
--- /dev/null
+++ b/components/layout/multicol.rs
@@ -0,0 +1,110 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! CSS Multi-column layout http://dev.w3.org/csswg/css-multicol/
+
+#![deny(unsafe_code)]
+
+use block::BlockFlow;
+use context::LayoutContext;
+use floats::FloatKind;
+use flow::{FlowClass, Flow};
+use fragment::{Fragment, FragmentBorderBoxIterator};
+use wrapper::ThreadSafeLayoutNode;
+
+use geom::{Point2D, Rect};
+use util::geometry::Au;
+use util::logical_geometry::LogicalRect;
+use std::fmt;
+use style::properties::ComputedValues;
+use std::sync::Arc;
+
+pub struct MulticolFlow {
+    pub block_flow: BlockFlow,
+}
+
+impl MulticolFlow {
+    pub fn from_node_and_fragment(node: &ThreadSafeLayoutNode,
+                                  fragment: Fragment,
+                                  float_kind: Option<FloatKind>)
+                                  -> MulticolFlow {
+        MulticolFlow {
+            block_flow: BlockFlow::from_node_and_fragment(node, fragment, float_kind)
+        }
+    }
+}
+
+impl Flow for MulticolFlow {
+    fn class(&self) -> FlowClass {
+        FlowClass::Multicol
+    }
+
+    fn as_multicol<'a>(&'a mut self) -> &'a mut MulticolFlow {
+        self
+    }
+
+    fn as_block<'a>(&'a mut self) -> &'a mut BlockFlow {
+        &mut self.block_flow
+    }
+
+    fn bubble_inline_sizes(&mut self) {
+        // FIXME(SimonSapin) http://dev.w3.org/csswg/css-sizing/#multicol-intrinsic
+        self.block_flow.bubble_inline_sizes();
+    }
+
+    fn assign_inline_sizes(&mut self, ctx: &LayoutContext) {
+        debug!("assign_inline_sizes({}): assigning inline_size for flow", "multicol");
+        self.block_flow.assign_inline_sizes(ctx);
+    }
+
+    fn assign_block_size<'a>(&mut self, ctx: &'a LayoutContext<'a>) {
+        debug!("assign_block_size: assigning block_size for multicol");
+        self.block_flow.assign_block_size(ctx);
+    }
+
+    fn compute_absolute_position(&mut self) {
+        self.block_flow.compute_absolute_position()
+    }
+
+    fn update_late_computed_inline_position_if_necessary(&mut self, inline_position: Au) {
+        self.block_flow.update_late_computed_inline_position_if_necessary(inline_position)
+    }
+
+    fn update_late_computed_block_position_if_necessary(&mut self, block_position: Au) {
+        self.block_flow.update_late_computed_block_position_if_necessary(block_position)
+    }
+
+    fn build_display_list(&mut self, layout_context: &LayoutContext) {
+        debug!("build_display_list_multicol: same process as block flow");
+        self.block_flow.build_display_list(layout_context)
+    }
+
+    fn repair_style(&mut self, new_style: &Arc<ComputedValues>) {
+        self.block_flow.repair_style(new_style)
+    }
+
+    fn compute_overflow(&self) -> Rect<Au> {
+        self.block_flow.compute_overflow()
+    }
+
+    fn generated_containing_block_rect(&self) -> LogicalRect<Au> {
+        self.block_flow.generated_containing_block_rect()
+    }
+
+    fn iterate_through_fragment_border_boxes(&self,
+                                             iterator: &mut FragmentBorderBoxIterator,
+                                             stacking_context_position: &Point2D<Au>) {
+        self.block_flow.iterate_through_fragment_border_boxes(iterator, stacking_context_position)
+    }
+
+    fn mutate_fragments(&mut self, mutator: &mut FnMut(&mut Fragment)) {
+        self.block_flow.mutate_fragments(mutator)
+    }
+}
+
+impl fmt::Debug for MulticolFlow {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "MulticolFlow: {:?}", self.block_flow)
+    }
+}
diff --git a/components/layout/table.rs b/components/layout/table.rs
index eeb11d4a29a..d6ad3746054 100644
--- a/components/layout/table.rs
+++ b/components/layout/table.rs
@@ -10,7 +10,6 @@ use block::{self, BlockFlow, CandidateBSizeIterator, ISizeAndMarginsComputer};
 use block::{ISizeConstraintInput, ISizeConstraintSolution};
 use context::LayoutContext;
 use display_list_builder::{BlockFlowDisplayListBuilding, BorderPaintingMode};
-use floats::FloatKind;
 use flow::{self, Flow, FlowClass, IMPACTED_BY_LEFT_FLOATS, IMPACTED_BY_RIGHT_FLOATS};
 use flow::{ImmutableFlowUtils};
 use fragment::{Fragment, FragmentBorderBoxIterator};
@@ -66,28 +65,7 @@ impl TableFlow {
     pub fn from_node_and_fragment(node: &ThreadSafeLayoutNode,
                                   fragment: Fragment)
                                   -> TableFlow {
-        let mut block_flow = BlockFlow::from_node_and_fragment(node, fragment);
-        let table_layout =
-            if block_flow.fragment().style().get_table().table_layout == table_layout::T::fixed {
-                TableLayout::Fixed
-            } else {
-                TableLayout::Auto
-            };
-        TableFlow {
-            block_flow: block_flow,
-            column_intrinsic_inline_sizes: Vec::new(),
-            column_computed_inline_sizes: Vec::new(),
-            collapsed_inline_direction_border_widths_for_table: Vec::new(),
-            collapsed_block_direction_border_widths_for_table: Vec::new(),
-            table_layout: table_layout
-        }
-    }
-
-    pub fn float_from_node_and_fragment(node: &ThreadSafeLayoutNode,
-                                        fragment: Fragment,
-                                        float_kind: FloatKind)
-                                        -> TableFlow {
-        let mut block_flow = BlockFlow::float_from_node_and_fragment(node, fragment, float_kind);
+        let mut block_flow = BlockFlow::from_node_and_fragment(node, fragment, None);
         let table_layout =
             if block_flow.fragment().style().get_table().table_layout == table_layout::T::fixed {
                 TableLayout::Fixed
diff --git a/components/layout/table_caption.rs b/components/layout/table_caption.rs
index 26e63c9d1b4..a476889ce0a 100644
--- a/components/layout/table_caption.rs
+++ b/components/layout/table_caption.rs
@@ -28,7 +28,7 @@ impl TableCaptionFlow {
     pub fn from_node_and_fragment(node: &ThreadSafeLayoutNode, fragment: Fragment)
                                   -> TableCaptionFlow {
         TableCaptionFlow {
-            block_flow: BlockFlow::from_node_and_fragment(node, fragment)
+            block_flow: BlockFlow::from_node_and_fragment(node, fragment, None)
         }
     }
 }
diff --git a/components/layout/table_cell.rs b/components/layout/table_cell.rs
index 6744fbc2106..8de69f0608d 100644
--- a/components/layout/table_cell.rs
+++ b/components/layout/table_cell.rs
@@ -52,7 +52,7 @@ impl TableCellFlow {
                                                   visible: bool)
                                                   -> TableCellFlow {
         TableCellFlow {
-            block_flow: BlockFlow::from_node_and_fragment(node, fragment),
+            block_flow: BlockFlow::from_node_and_fragment(node, fragment, None),
             collapsed_borders: CollapsedBordersForCell::new(),
             column_span: node.get_unsigned_integer_attribute(UnsignedIntegerAttribute::ColSpan)
                              .unwrap_or(1),
diff --git a/components/layout/table_row.rs b/components/layout/table_row.rs
index 3beeb1f7fe2..a453003e19e 100644
--- a/components/layout/table_row.rs
+++ b/components/layout/table_row.rs
@@ -79,7 +79,7 @@ impl TableRowFlow {
     pub fn from_node_and_fragment(node: &ThreadSafeLayoutNode, fragment: Fragment)
                                   -> TableRowFlow {
         TableRowFlow {
-            block_flow: BlockFlow::from_node_and_fragment(node, fragment),
+            block_flow: BlockFlow::from_node_and_fragment(node, fragment, None),
             cell_intrinsic_inline_sizes: Vec::new(),
             column_computed_inline_sizes: Vec::new(),
             spacing: border_spacing::T {
diff --git a/components/layout/table_rowgroup.rs b/components/layout/table_rowgroup.rs
index e442f2b4c7b..8990b127da4 100644
--- a/components/layout/table_rowgroup.rs
+++ b/components/layout/table_rowgroup.rs
@@ -62,7 +62,7 @@ impl TableRowGroupFlow {
     pub fn from_node_and_fragment(node: &ThreadSafeLayoutNode, fragment: Fragment)
                                   -> TableRowGroupFlow {
         TableRowGroupFlow {
-            block_flow: BlockFlow::from_node_and_fragment(node, fragment),
+            block_flow: BlockFlow::from_node_and_fragment(node, fragment, None),
             column_intrinsic_inline_sizes: Vec::new(),
             column_computed_inline_sizes: Vec::new(),
             spacing: border_spacing::T {
diff --git a/components/layout/table_wrapper.rs b/components/layout/table_wrapper.rs
index 5db3674341c..7369acbbf4c 100644
--- a/components/layout/table_wrapper.rs
+++ b/components/layout/table_wrapper.rs
@@ -56,9 +56,11 @@ pub struct TableWrapperFlow {
 }
 
 impl TableWrapperFlow {
-    pub fn from_node_and_fragment(node: &ThreadSafeLayoutNode, fragment: Fragment)
+    pub fn from_node_and_fragment(node: &ThreadSafeLayoutNode,
+                                  fragment: Fragment,
+                                  float_kind: Option<FloatKind>)
                                   -> TableWrapperFlow {
-        let mut block_flow = BlockFlow::from_node_and_fragment(node, fragment);
+        let mut block_flow = BlockFlow::from_node_and_fragment(node, fragment, float_kind);
         let table_layout = if block_flow.fragment().style().get_table().table_layout ==
                               table_layout::T::fixed {
             TableLayout::Fixed
@@ -71,25 +73,6 @@ impl TableWrapperFlow {
             table_layout: table_layout
         }
     }
-
-    pub fn float_from_node_and_fragment(node: &ThreadSafeLayoutNode,
-                                        fragment: Fragment,
-                                        float_kind: FloatKind)
-                                        -> TableWrapperFlow {
-        let mut block_flow = BlockFlow::float_from_node_and_fragment(node, fragment, float_kind);
-        let table_layout = if block_flow.fragment().style().get_table().table_layout ==
-                              table_layout::T::fixed {
-            TableLayout::Fixed
-        } else {
-            TableLayout::Auto
-        };
-        TableWrapperFlow {
-            block_flow: block_flow,
-            column_intrinsic_inline_sizes: vec!(),
-            table_layout: table_layout
-        }
-    }
-
     fn border_padding_and_spacing(&mut self) -> (Au, Au) {
         let (mut table_border_padding, mut spacing) = (Au(0), Au(0));
         for kid in self.block_flow.base.child_iter() {
diff --git a/components/script/dom/webidls/CSSStyleDeclaration.webidl b/components/script/dom/webidls/CSSStyleDeclaration.webidl
index e937f4c41b2..8ed0805f432 100644
--- a/components/script/dom/webidls/CSSStyleDeclaration.webidl
+++ b/components/script/dom/webidls/CSSStyleDeclaration.webidl
@@ -187,6 +187,11 @@ partial interface CSSStyleDeclaration {
 
   [TreatNullAs=EmptyString] attribute DOMString imageRendering;
 
+  [TreatNullAs=EmptyString] attribute DOMString columnCount;
+  [TreatNullAs=EmptyString] attribute DOMString columnWidth;
+  [TreatNullAs=EmptyString] attribute DOMString columns;
+  [TreatNullAs=EmptyString] attribute DOMString columnGap;
+
   [TreatNullAs=EmptyString] attribute DOMString transition;
   [TreatNullAs=EmptyString] attribute DOMString transitionDuration;
   [TreatNullAs=EmptyString] attribute DOMString transitionTimingFunction;
diff --git a/components/style/properties.mako.rs b/components/style/properties.mako.rs
index 97720a5dcd6..8012bfc9683 100644
--- a/components/style/properties.mako.rs
+++ b/components/style/properties.mako.rs
@@ -60,11 +60,12 @@ class Longhand(object):
             self.derived_from = [ to_rust_ident(name) for name in derived_from ]
 
 class Shorthand(object):
-    def __init__(self, name, sub_properties):
+    def __init__(self, name, sub_properties, experimental=False):
         self.name = name
         self.ident = to_rust_ident(name)
         self.camel_case = to_camel_case(self.ident)
         self.derived_from = None
+        self.experimental = experimental
         self.sub_properties = [LONGHANDS_BY_NAME[s] for s in sub_properties]
 
 class StyleStruct(object):
@@ -2177,6 +2178,167 @@ pub mod longhands {
     // TODO(pcwalton): SVG-only values.
     ${single_keyword("pointer-events", "auto none")}
 
+
+    ${new_style_struct("Column", is_inherited=False)}
+
+    <%self:longhand name="column-width" experimental="True">
+        use values::computed::{ToComputedValue, Context};
+        use cssparser::ToCss;
+        use text_writer::{self, TextWriter};
+
+        #[derive(Clone, Copy, PartialEq)]
+        pub enum SpecifiedValue {
+            Auto,
+            Specified(specified::Length),
+        }
+
+        impl ToCss for SpecifiedValue {
+            fn to_css<W>(&self, dest: &mut W) -> text_writer::Result where W: TextWriter {
+                match *self {
+                    SpecifiedValue::Auto => dest.write_str("auto"),
+                    SpecifiedValue::Specified(l) => l.to_css(dest),
+                }
+            }
+        }
+
+        pub mod computed_value {
+            use util::geometry::Au;
+            pub type T = Option<Au>;
+        }
+
+        #[inline]
+        pub fn get_initial_value() -> computed_value::T {
+            None
+        }
+
+        impl ToComputedValue for SpecifiedValue {
+            type ComputedValue = computed_value::T;
+
+            #[inline]
+            fn to_computed_value(&self, context: &Context) -> computed_value::T {
+                match *self {
+                    SpecifiedValue::Auto => None,
+                    SpecifiedValue::Specified(l) => Some(l.to_computed_value(context))
+                }
+            }
+        }
+
+        pub fn parse(_context: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue, ()> {
+            if input.try(|input| input.expect_ident_matching("auto")).is_ok() {
+                Ok(SpecifiedValue::Auto)
+            } else {
+                specified::Length::parse_non_negative(input).map(SpecifiedValue::Specified)
+            }
+        }
+    </%self:longhand>
+
+    <%self:longhand name="column-count" experimental="True">
+        use values::computed::{ToComputedValue, Context};
+        use cssparser::ToCss;
+        use text_writer::{self, TextWriter};
+
+        #[derive(Clone, Copy, PartialEq)]
+        pub enum SpecifiedValue {
+            Auto,
+            Specified(u32),
+        }
+
+        impl ToCss for SpecifiedValue {
+            fn to_css<W>(&self, dest: &mut W) -> text_writer::Result where W: TextWriter {
+                match *self {
+                    SpecifiedValue::Auto => dest.write_str("auto"),
+                    SpecifiedValue::Specified(count) => write!(dest, "{}", count),
+                }
+            }
+        }
+
+        pub mod computed_value {
+            pub type T = Option<u32>;
+        }
+
+        #[inline]
+        pub fn get_initial_value() -> computed_value::T {
+            None
+        }
+
+        impl ToComputedValue for SpecifiedValue {
+            type ComputedValue = computed_value::T;
+
+            #[inline]
+            fn to_computed_value(&self, _context: &Context) -> computed_value::T {
+                match *self {
+                    SpecifiedValue::Auto => None,
+                    SpecifiedValue::Specified(count) => Some(count)
+                }
+            }
+        }
+
+        pub fn parse(_context: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue, ()> {
+            if input.try(|input| input.expect_ident_matching("auto")).is_ok() {
+                Ok(SpecifiedValue::Auto)
+            } else {
+                use std::u32;
+                let count = try!(input.expect_integer());
+                // Zero is invalid
+                if count <= 0 || count > (u32::MAX as i64) {
+                    return Err(())
+                }
+                Ok(SpecifiedValue::Specified(count as u32))
+            }
+        }
+    </%self:longhand>
+
+    <%self:longhand name="column-gap" experimental="True">
+        use values::computed::{ToComputedValue, Context};
+        use cssparser::ToCss;
+        use text_writer::{self, TextWriter};
+
+        #[derive(Clone, Copy, PartialEq)]
+        pub enum SpecifiedValue {
+            Normal,
+            Specified(specified::Length),
+        }
+
+        impl ToCss for SpecifiedValue {
+            fn to_css<W>(&self, dest: &mut W) -> text_writer::Result where W: TextWriter {
+                match *self {
+                    SpecifiedValue::Normal => dest.write_str("normal"),
+                    SpecifiedValue::Specified(l) => l.to_css(dest),
+                }
+            }
+        }
+
+        pub mod computed_value {
+            use util::geometry::Au;
+            pub type T = Option<Au>;
+        }
+
+        #[inline]
+        pub fn get_initial_value() -> computed_value::T {
+            None
+        }
+
+        impl ToComputedValue for SpecifiedValue {
+            type ComputedValue = computed_value::T;
+
+            #[inline]
+            fn to_computed_value(&self, context: &Context) -> computed_value::T {
+                match *self {
+                    SpecifiedValue::Normal => None,
+                    SpecifiedValue::Specified(l) => Some(l.to_computed_value(context))
+                }
+            }
+        }
+
+        pub fn parse(_context: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue, ()> {
+            if input.try(|input| input.expect_ident_matching("normal")).is_ok() {
+                Ok(SpecifiedValue::Normal)
+            } else {
+                specified::Length::parse_non_negative(input).map(SpecifiedValue::Specified)
+            }
+        }
+    </%self:longhand>
+
     // Box-shadow, etc.
     ${new_style_struct("Effects", is_inherited=False)}
 
@@ -3952,9 +4114,9 @@ pub mod shorthands {
     use parser::ParserContext;
     use values::specified;
 
-    <%def name="shorthand(name, sub_properties)">
+    <%def name="shorthand(name, sub_properties, experimental=False)">
     <%
-        shorthand = Shorthand(name, sub_properties.split())
+        shorthand = Shorthand(name, sub_properties.split(), experimental=experimental)
         SHORTHANDS.append(shorthand)
     %>
         pub mod ${shorthand.ident} {
@@ -4439,6 +4601,47 @@ pub mod shorthands {
         }
     </%self:shorthand>
 
+    <%self:shorthand name="columns" sub_properties="column-count column-width" experimental="True">
+        use properties::longhands::{column_count, column_width};
+        let mut column_count = None;
+        let mut column_width = None;
+        let mut autos = 0;
+
+        loop {
+            if input.try(|input| input.expect_ident_matching("auto")).is_ok() {
+                // Leave the options to None, 'auto' is the initial value.
+                autos += 1;
+                continue
+            }
+
+            if column_count.is_none() {
+                if let Ok(value) = input.try(|input| column_count::parse(context, input)) {
+                    column_count = Some(value);
+                    continue
+                }
+            }
+
+            if column_width.is_none() {
+                if let Ok(value) = input.try(|input| column_width::parse(context, input)) {
+                    column_width = Some(value);
+                    continue
+                }
+            }
+
+            break
+        }
+
+        let values = autos + column_count.iter().len() + column_width.iter().len();
+        if values == 0 || values > 2 {
+            Err(())
+        } else {
+            Ok(Longhands {
+                column_count: column_count,
+                column_width: column_width,
+            })
+        }
+    </%self:shorthand>
+
     <%self:shorthand name="overflow" sub_properties="overflow-x overflow-y">
         use properties::longhands::{overflow_x, overflow_y};
 
@@ -4802,6 +5005,11 @@ impl PropertyDeclaration {
             % endfor
             % for shorthand in SHORTHANDS:
                 "${shorthand.name}" => {
+                    % if shorthand.experimental:
+                        if !::util::opts::experimental_enabled() {
+                            return PropertyDeclarationParseResult::ExperimentalProperty
+                        }
+                    % endif
                     match input.try(CSSWideKeyword::parse) {
                         Ok(CSSWideKeyword::InheritKeyword) => {
                             % for sub_property in shorthand.sub_properties:
@@ -4987,6 +5195,12 @@ impl ComputedValues {
     }
 
     #[inline]
+    pub fn is_multicol(&self) -> bool {
+        let style = self.get_column();
+        style.column_count.is_some() || style.column_width.is_some()
+    }
+
+    #[inline]
     pub fn get_font_arc(&self) -> Arc<style_structs::Font> {
         self.font.clone()
     }