Implement non-zero dimension attribute parsing

Fixes #8445

The only attributes I found that we have implemented that uses non-zero
dimenion attributes:

* `width` for `<td>` and `<th>` (table cells)
* `width` for `<table>`

I updated these implementations to use the new non-zero dimension
attribute parsing and added associated regression tests.

1 files changed, 6 insertions, 1 deletions

diff --git a/components/style/attr.rs b/components/style/attr.rs
index 0569b235a9c..aa7eb621839 100644
--- a/components/style/attr.rs
+++ b/components/style/attr.rs
@@ -6,7 +6,7 @@ use cssparser::RGBA;
 use std::ops::Deref;
 use string_cache::{Atom, Namespace};
 use util::str::{DOMString, LengthOrPercentageOrAuto, parse_unsigned_integer, parse_legacy_color, parse_length};
-use util::str::{split_html_space_chars, str_join, parse_integer};
+use util::str::{parse_nonzero_length, split_html_space_chars, str_join, parse_integer};
 use values::specified::{Length};
 
 // Duplicated from script::dom::values.
@@ -96,6 +96,11 @@ impl AttrValue {
         AttrValue::Dimension(string, parsed)
     }
 
+    pub fn from_nonzero_dimension(string: DOMString) -> AttrValue {
+        let parsed = parse_nonzero_length(&string);
+        AttrValue::Dimension(string, parsed)
+    }
+
     /// Assumes the `AttrValue` is a `TokenList` and returns its tokens
     ///
     /// ## Panics