Web Animations API: Don't allow quirky CSS values in keyframes

Source/core/animation/StringKeyframe.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef StringKeyframe_h
 #define StringKeyframe_h
 
 #include "core/animation/Keyframe.h"
 #include "core/css/StylePropertySet.h"
 
@@ skipping 77 matching lines @@
     private:
         SVGPropertySpecificKeyframe(double offset, PassRefPtr<TimingFunction> easing, const String&);
 
         bool isSVGPropertySpecificKeyframe() const override { return true; }
 
         String m_value;
     };
 
 private:
     StringKeyframe()
-        : m_propertySet(MutableStylePropertySet::create(HTMLQuirksMode))
+        : m_propertySet(MutableStylePropertySet::create(HTMLStandardMode))
     { }
 
     StringKeyframe(const StringKeyframe& copyFrom);
 
     PassRefPtrWillBeRawPtr<Keyframe> clone() const override;
     PassOwnPtrWillBeRawPtr<Keyframe::PropertySpecificKeyframe> createPropertySpecificKeyframe(PropertyHandle) const override;
 
     bool isStringKeyframe() const override { return true; }
 
     RefPtrWillBeMember<MutableStylePropertySet> m_propertySet;
     HashMap<const QualifiedName*, String> m_svgPropertyMap;
 };
 
 using CSSPropertySpecificKeyframe = StringKeyframe::CSSPropertySpecificKeyframe;
 using SVGPropertySpecificKeyframe = StringKeyframe::SVGPropertySpecificKeyframe;
 
 DEFINE_TYPE_CASTS(StringKeyframe, Keyframe, value, value->isStringKeyframe(), value.isStringKeyframe());
 DEFINE_TYPE_CASTS(CSSPropertySpecificKeyframe, Keyframe::PropertySpecificKeyframe, value, value->isCSSPropertySpecificKeyframe(), value.isCSSPropertySpecificKeyframe());
 DEFINE_TYPE_CASTS(SVGPropertySpecificKeyframe, Keyframe::PropertySpecificKeyframe, value, value->isSVGPropertySpecificKeyframe(), value.isSVGPropertySpecificKeyframe());
 
 }
 
 #endif