Change first() and second() in CSSPairValue to return const references

Source/core/css/BasicShapeFunctions.cpp

 /*
  * Copyright (C) 2012 Adobe Systems Incorporated. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above
  *    copyright notice, this list of conditions and the following
  *    disclaimer.
@@ skipping 122 matching lines @@
     if (!value)
         return Length(0, Fixed);
     return value->convertToLength(state.cssToLengthConversionData());
 }
 
 static LengthSize convertToLengthSize(const StyleResolverState& state, CSSValuePair* value)
 {
     if (!value)
         return LengthSize(Length(0, Fixed), Length(0, Fixed));
 
-    return LengthSize(convertToLength(state, toCSSPrimitiveValue(value->first())), convertToLength(state, toCSSPrimitiveValue(value->second())));
+    return LengthSize(convertToLength(state, &toCSSPrimitiveValue(value->first())), convertToLength(state, &toCSSPrimitiveValue(value->second())));
 }
 
 static BasicShapeCenterCoordinate convertToCenterCoordinate(const StyleResolverState& state, CSSValue* value)
 {
     BasicShapeCenterCoordinate::Direction direction;
     Length offset = Length(0, Fixed);
 
     CSSValueID keyword = CSSValueTop;
     if (!value) {
         keyword = CSSValueCenter;
     } else if (value->isPrimitiveValue() && toCSSPrimitiveValue(value)->isValueID()) {
         keyword = toCSSPrimitiveValue(value)->getValueID();
     } else if (value->isValuePair()) {
-        keyword = toCSSPrimitiveValue(toCSSValuePair(value)->first())->getValueID();
-        offset = convertToLength(state, toCSSPrimitiveValue(toCSSValuePair(value)->second()));
+        keyword = toCSSPrimitiveValue(toCSSValuePair(value)->first()).getValueID();
+        offset = convertToLength(state, &toCSSPrimitiveValue(toCSSValuePair(value)->second()));
     } else {
         offset = convertToLength(state, toCSSPrimitiveValue(value));
     }
 
     switch (keyword) {
     case CSSValueTop:
     case CSSValueLeft:
         direction = BasicShapeCenterCoordinate::TopLeft;
         break;
     case CSSValueRight:
@@ skipping 98 matching lines @@
 }
 
 FloatPoint floatPointForCenterCoordinate(const BasicShapeCenterCoordinate& centerX, const BasicShapeCenterCoordinate& centerY, FloatSize boxSize)
 {
     float x = floatValueForLength(centerX.computedLength(), boxSize.width());
     float y = floatValueForLength(centerY.computedLength(), boxSize.height());
     return FloatPoint(x, y);
 }
 
 }