Implement color stop position syntax from CSS Image Values 4

third_party/WebKit/Source/core/css/parser/CSSPropertyParserHelpers.cpp

Index: third_party/WebKit/Source/core/css/parser/CSSPropertyParserHelpers.cpp
diff --git a/third_party/WebKit/Source/core/css/parser/CSSPropertyParserHelpers.cpp b/third_party/WebKit/Source/core/css/parser/CSSPropertyParserHelpers.cpp
index 4f6e0cecc6c56aba31b4fc746fdb41599975ef8b..5156758a1c05bfb2377bb6b2df89427ed2d3e9a6 100644
--- a/third_party/WebKit/Source/core/css/parser/CSSPropertyParserHelpers.cpp
+++ b/third_party/WebKit/Source/core/css/parser/CSSPropertyParserHelpers.cpp
@@ -967,6 +967,17 @@ static bool consumeGradientColorStops(CSSParserTokenRange& range,
     if (!stop.m_color && !stop.m_offset)
       return false;
     gradient->addStop(stop);
+
+    if (RuntimeEnabledFeatures::multipleColorStopPositionsEnabled()) {
+      if (!stop.m_color || !stop.m_offset)
+        continue;
+
+      // Optional second position.
+      stop.m_offset = consumePositionFunc(range, cssParserMode, ValueRangeAll,
+                                          UnitlessQuirk::Forbid);
+      if (stop.m_offset)
+        gradient->addStop(stop);
+    }
   } while (consumeCommaIncludingWhitespace(range));
 
   // The last color stop cannot be a color hint.