Allow determining if an SVG value has been specified

Source/core/svg/properties/NewSVGAnimatedProperty.cpp

Index: Source/core/svg/properties/NewSVGAnimatedProperty.cpp
diff --git a/Source/core/svg/properties/NewSVGAnimatedProperty.cpp b/Source/core/svg/properties/NewSVGAnimatedProperty.cpp
index af64b7a5b0586afbf37580dd75c3a668419c93ed..492d1e5d6f3d5b244d92b0d6f192b490ed915137 100644
--- a/Source/core/svg/properties/NewSVGAnimatedProperty.cpp
+++ b/Source/core/svg/properties/NewSVGAnimatedProperty.cpp
@@ -81,6 +81,11 @@ void NewSVGAnimatedPropertyBase::synchronizeAttribute()
     m_contextElement->setSynchronizedLazyAttribute(m_attributeName, value);
 }
 
+bool NewSVGAnimatedPropertyBase::isSpecified() const
+{
+    return isAnimating() || contextElement()->hasAttribute(attributeName());
+}
+
 void NewSVGAnimatedPropertyBase::commitChange()
 {
     contextElement()->invalidateSVGAttributes();