Add support for the object-position CSS property.

Source/core/css/resolver/StyleBuilderCustom.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
  * copyright notice, this list of conditions and the following disclaimer
  * in the documentation and/or other materials provided with the
  * distribution.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 26 matching lines @@
 // Note that we assume the parser only allows valid CSSValue types.
 
 class StyleBuilderConverter {
 public:
     template <typename T> static T convertComputedLength(StyleResolverState&, CSSValue*);
     template <typename T> static T convertLineWidth(StyleResolverState&, CSSValue*);
     static Length convertLength(StyleResolverState&, CSSValue*);
     static Length convertLengthOrAuto(StyleResolverState&, CSSValue*);
     static Length convertLengthSizing(StyleResolverState&, CSSValue*);
     static Length convertLengthMaxSizing(StyleResolverState&, CSSValue*);
+    static LengthPoint convertLengthPoint(StyleResolverState&, CSSValue*);
     static LengthSize convertRadius(StyleResolverState&, CSSValue*);
     static float convertSpacing(StyleResolverState&, CSSValue*);
     template <CSSValueID IdForNone> static AtomicString convertString(StyleResolverState&, CSSValue*);
 };
 
 template <typename T>
 T StyleBuilderConverter::convertComputedLength(StyleResolverState& state, CSSValue* value)
 {
     CSSPrimitiveValue* primitiveValue = toCSSPrimitiveValue(value);
     float zoom = state.style()->effectiveZoom();
@@ skipping 32 matching lines @@
 {
     CSSPrimitiveValue* primitiveValue = toCSSPrimitiveValue(value);
     if (primitiveValue->getValueID() == IdForNone)
         return nullAtom;
     return primitiveValue->getStringValue();
 }
 
 } // namespace WebCore
 
 #endif