Auto merge of #18933 - mrobinson:wr-text-index, r=jdm

Use WebRender to compute text index on click events

This is the second half of switching over to WebRender for hit testing.
Now that WebRender gives us the location of the hit tested point in the
display item, we can use that to calculate text index.

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- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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- [ ] There are tests for these changes OR
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1 files changed, 11 insertions, 10 deletions

diff --git a/components/layout_thread/lib.rs b/components/layout_thread/lib.rs
index 0010d66673c..e7ce75db5c1 100644
--- a/components/layout_thread/lib.rs
+++ b/components/layout_thread/lib.rs
@@ -1361,18 +1361,19 @@ impl LayoutThread {
                 let node = unsafe { ServoLayoutNode::new(&node) };
                 rw_data.content_boxes_response = process_content_boxes_request(node, root_flow);
             },
-            ReflowGoal::TextIndexQuery(node, mouse_x, mouse_y) => {
+            ReflowGoal::TextIndexQuery(node, point_in_node) => {
                 let node = unsafe { ServoLayoutNode::new(&node) };
                 let opaque_node = node.opaque();
-                let client_point = Point2D::new(Au::from_px(mouse_x),
-                                                Au::from_px(mouse_y));
-                rw_data.text_index_response =
-                    TextIndexResponse(rw_data.display_list
-                                      .as_ref()
-                                      .expect("Tried to hit test with no display list")
-                                      .text_index(opaque_node,
-                                                  &client_point,
-                                                  &rw_data.scroll_offsets));
+                let point_in_node = Point2D::new(
+                    Au::from_f32_px(point_in_node.x),
+                    Au::from_f32_px(point_in_node.y)
+                );
+                rw_data.text_index_response = TextIndexResponse(
+                    rw_data.display_list
+                    .as_ref()
+                    .expect("Tried to hit test with no display list")
+                    .text_index(opaque_node, &point_in_node)
+                );
             },
             ReflowGoal::NodeGeometryQuery(node) => {
                 let node = unsafe { ServoLayoutNode::new(&node) };