Adding support for color interpolation hints to CSS gradients.

Source/core/css/parser/CSSPropertyParser.cpp

 /*
  * Copyright (C) 2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2012 Adobe Systems Incorporated. All rights reserved.
  * Copyright (C) 2012 Intel Corporation. All rights reserved.
  *
@@ skipping 6806 matching lines @@
 
     gradient = result.release();
     return true;
 }
 
 bool CSSPropertyParser::parseGradientColorStops(CSSParserValueList* valueList, CSSGradientValue* gradient, bool expectComma)
 {
     CSSParserValue* a = valueList->current();
 
     // Now look for color stops.
+    // <color-stop-list> = [ <color-stop> , <color-hint>? ]# , <color-stop>
+    bool supportsColorHints = gradient->gradientType() == CSSLinearGradient
+        || gradient->gradientType() == CSSRadialGradient;
+
+    // The first color stop cannot be a color hint.
+    bool previousStopWasColorHint = true;
     while (a) {
         // Look for the comma before the next stop.
         if (expectComma) {
             if (!isComma(a))
                 return false;
 
             a = valueList->next();
             if (!a)
                 return false;
         }
 
         // <color-stop> = <color> [ <percentage> | <length> ]?
+        // <color-hint> = <length> | <percentage>
         CSSGradientColorStop stop;
         stop.m_color = parseGradientColorOrKeyword(this, a);
-        if (!stop.m_color)
+
+        // Two hints in a row are not allowed.
+        if (!stop.m_color && (!supportsColorHints || previousStopWasColorHint))
             return false;
+        previousStopWasColorHint = !stop.m_color;
 
-        a = valueList->next();
+        if (stop.m_color)
+            a = valueList->next();
+
         if (a) {
             if (validUnit(a, FLength | FPercent)) {
                 stop.m_position = createPrimitiveNumericValue(a);
                 a = valueList->next();
             }
         }
 
+        if (!stop.m_color && !stop.m_position)
+            return false;
+
         gradient->addStop(stop);
         expectComma = true;
     }
 
+    // The last color stop cannot be a color hint.
+    if (previousStopWasColorHint)
+        return false;
+
     // Must have 2 or more stops to be valid.
     return gradient->stopCount() >= 2;
 }
 
 bool CSSPropertyParser::parseGeneratedImage(CSSParserValueList* valueList, RefPtrWillBeRawPtr<CSSValue>& value)
 {
     CSSParserValue* val = valueList->current();
 
     if (val->unit != CSSParserValue::Function)
         return false;
@@ skipping 1511 matching lines @@
             return nullptr;
         a = args->next();
 
         argNumber++;
     }
 
     return transformValue.release();
 }
 
 } // namespace blink