[CSS Grid Layout] Use CSS_FR for flexible lengths instead of CSS_DIMENSION

Source/core/css/resolver/StyleBuilderCustom.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
@@ skipping 928 matching lines @@
         return true;
     }
 
     if (primitiveValue->getValueID() == CSSValueMaxContent) {
         workingLength = Length(MaxContent);
         return true;
     }
 
     if (primitiveValue->isFlex()) {
         // Fractional unit.
-        workingLength.setFlex(primitiveValue->getFloatValue());
+        workingLength.setFlex(primitiveValue->getDoubleValue());
         return true;
     }
 
     workingLength = primitiveValue->convertToLength<FixedIntegerConversion | PercentConversion | AutoConversion>(state.style(), state.rootElementStyle(), state.style()->effectiveZoom());
     if (workingLength.length().isUndefined())
         return false;
 
     if (primitiveValue->isLength())
         workingLength.length().setQuirk(primitiveValue->isQuirkValue());
 
@@ skipping 1435 matching lines @@
         break;
     }
     case CSSPropertyEnableBackground:
         // Silently ignoring this property for now
         // http://bugs.webkit.org/show_bug.cgi?id=6022
         break;
     }
 }
 
 } // namespace WebCore