Remove support for the externalResourcesRequired attribute.

Source/core/svg/SVGSymbolElement.cpp

Index: Source/core/svg/SVGSymbolElement.cpp
diff --git a/Source/core/svg/SVGSymbolElement.cpp b/Source/core/svg/SVGSymbolElement.cpp
index b9a405ad02790f37fbeda30fb2cf5d3955ab9ec7..aace9b2b2ccefc3287fc7e8a7c475aaca18f8581 100644
--- a/Source/core/svg/SVGSymbolElement.cpp
+++ b/Source/core/svg/SVGSymbolElement.cpp
@@ -29,12 +29,10 @@
 namespace WebCore {
 
 // Animated property definitions
-DEFINE_ANIMATED_BOOLEAN(SVGSymbolElement, SVGNames::externalResourcesRequiredAttr, ExternalResourcesRequired, externalResourcesRequired)
 DEFINE_ANIMATED_PRESERVEASPECTRATIO(SVGSymbolElement, SVGNames::preserveAspectRatioAttr, PreserveAspectRatio, preserveAspectRatio)
 DEFINE_ANIMATED_RECT(SVGSymbolElement, SVGNames::viewBoxAttr, ViewBox, viewBox)
 
 BEGIN_REGISTER_ANIMATED_PROPERTIES(SVGSymbolElement)
-    REGISTER_LOCAL_ANIMATED_PROPERTY(externalResourcesRequired)
     REGISTER_LOCAL_ANIMATED_PROPERTY(viewBox)
     REGISTER_LOCAL_ANIMATED_PROPERTY(preserveAspectRatio)
     REGISTER_PARENT_ANIMATED_PROPERTIES(SVGElement)
@@ -55,10 +53,9 @@ PassRefPtr<SVGSymbolElement> SVGSymbolElement::create(Document& document)
 bool SVGSymbolElement::isSupportedAttribute(const QualifiedName& attrName)
 {
     DEFINE_STATIC_LOCAL(HashSet<QualifiedName>, supportedAttributes, ());
-    if (supportedAttributes.isEmpty()) {
-        SVGExternalResourcesRequired::addSupportedAttributes(supportedAttributes);
+    if (supportedAttributes.isEmpty())
         SVGFitToViewBox::addSupportedAttributes(supportedAttributes);
-    }
+
     return supportedAttributes.contains<SVGAttributeHashTranslator>(attrName);
 }
 
@@ -69,8 +66,6 @@ void SVGSymbolElement::parseAttribute(const QualifiedName& name, const AtomicStr
         return;
     }
 
-    if (SVGExternalResourcesRequired::parseAttribute(name, value))
-        return;
     if (SVGFitToViewBox::parseAttribute(this, name, value))
         return;