New parser mode for CSSOM @viewport descriptors.

Source/core/css/StylePropertySet.h

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2008, 2012 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 106 matching lines @@
 
     static unsigned averageSizeInBytes();
 
 #ifndef NDEBUG
     void showStyle();
 #endif
 
     bool propertyMatches(CSSPropertyID, const CSSValue*) const;
 
 protected:
+
+    enum { MaxArraySize = (1 << 28) - 1 };
+
     StylePropertySet(CSSParserMode cssParserMode)
         : m_cssParserMode(cssParserMode)
         , m_isMutable(true)
         , m_arraySize(0)
     { }
 
     StylePropertySet(CSSParserMode cssParserMode, unsigned immutableArraySize)
         : m_cssParserMode(cssParserMode)
         , m_isMutable(false)
-        , m_arraySize(immutableArraySize)
+        , m_arraySize(std::min(immutableArraySize, unsigned(MaxArraySize)))

[eseidel, 2013/09/17 16:28:55]

Do we have any asserts on array modification which need to be changed?

[rune, 2013/09/17 20:17:03]

So, m_arraySize won't change after the initialization. For mutable property
sets, the size of m_propertyVector is used as the property count instead.

But, there's a use of the non-clamped length in the ImmutablePropertySet
constructor that needs to be fixed.

[rune, 2013/09/17 20:40:41]

Done.

     { }
 
-    unsigned m_cssParserMode : 2;
+    unsigned m_cssParserMode : 3;
     mutable unsigned m_isMutable : 1;
-    unsigned m_arraySize : 29;
+    unsigned m_arraySize : 28;
 
     friend class PropertySetCSSStyleDeclaration;
 };
 
 class ImmutableStylePropertySet : public StylePropertySet {
 public:
     ~ImmutableStylePropertySet();
     static PassRefPtr<ImmutableStylePropertySet> create(const CSSProperty* properties, unsigned count, CSSParserMode);
 
     unsigned propertyCount() const { return m_arraySize; }
@@ skipping 104 matching lines @@
 
     if (m_isMutable)
         delete static_cast<MutableStylePropertySet*>(this);
     else
         delete static_cast<ImmutableStylePropertySet*>(this);
 }
 
 } // namespace WebCore
 
 #endif // StylePropertySet_h