Fix SVG animations which check viewBox attribute

Source/core/svg/SVGViewSpec.h

Index: Source/core/svg/SVGViewSpec.h
diff --git a/Source/core/svg/SVGViewSpec.h b/Source/core/svg/SVGViewSpec.h
index c4a393eab97c355924da48e86a69952ce9fd0283..1d078452e18358db31fcfc8b7590433bc5978bbc 100644
--- a/Source/core/svg/SVGViewSpec.h
+++ b/Source/core/svg/SVGViewSpec.h
@@ -77,7 +77,7 @@ private:
 template <typename T>
 void SVGViewSpec::inheritViewAttributesFromElement(T* inheritFromElement)
 {
-    if (inheritFromElement->hasAttribute(SVGNames::viewBoxAttr))
+    if (!inheritFromElement->hasEmptyViewBox())
         viewBox()->baseValue()->setValue(inheritFromElement->viewBox()->currentValue()->value());

[fs, 2015/04/22 10:56:51]

This will just snapshot the value, which likely mean that viewBox animations
combined with fragment view-specs won't work great. That seems to be a
pre-existing condition though, so the not the fault of this CL.

 
     if (inheritFromElement->hasAttribute(SVGNames::preserveAspectRatioAttr)) {