Reintroducing parse_a_sizes

components/script/dom/htmlimageelement.rs

@@ -3,6 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use app_units::{Au, AU_PER_PX};
+use cssparser::{Parser, ParserInput};
 use document_loader::{LoadType, LoadBlocker};
 use dom::activation::Activatable;
 use dom::attr::Attr;
@@ -57,7 +58,12 @@ use std::default::Default;
 use std::i32;
 use std::sync::{Arc, Mutex};
 use style::attr::{AttrValue, LengthOrPercentageOrAuto, parse_double, parse_unsigned_integer};
+use style::context::QuirksMode;
+use style::parser::ParserContext;
 use style::str::is_ascii_digit;
+use style::stylesheets::{CssRuleType, Origin};
+use style::values::specified::{source_size_list::SourceSizeList};
+use style_traits::ParsingMode;
 use task_source::{TaskSource, TaskSourceName};
 
 enum ParseState {
@@ -1010,6 +1016,22 @@ pub fn collect_sequence_characters<F>(s: &str, predicate: F) -> (&str, &str)
     return (s, "");
 }
 
+//https://html.spec.whatwg.org/multipage/#parse-a-sizes-attribute
+pub fn parse_a_sizes_attribute(value: DOMString) -> SourceSizeList {
+    let mut input = ParserInput::new(&value);
+    let mut parser = Parser::new(&mut input);
+    let url = ServoUrl::parse("about:blank").unwrap();
+    let context = ParserContext::new(
+        Origin::Author,
+        &url,
+        Some(CssRuleType::Style),
+        ParsingMode::empty(),
+        QuirksMode::NoQuirks,
+        None,
+    );
+    SourceSizeList::parse(&context, &mut parser)
+}
+
 /// Parse an `srcset` attribute - https://html.spec.whatwg.org/multipage/#parsing-a-srcset-attribute.
 pub fn parse_a_srcset_attribute(input: &str) -> Vec<ImageSource> {
     let mut url_len = 0;