Remove support for the externalResourcesRequired attribute.

Source/core/svg/SVGClipPathElement.h

Index: Source/core/svg/SVGClipPathElement.h
diff --git a/Source/core/svg/SVGClipPathElement.h b/Source/core/svg/SVGClipPathElement.h
index d098e69ba1bd95696ea6e9cddd0e4490dff2a7d6..a3a2f58c702610428e6372df2c4a8e6f0dcd0517 100644
--- a/Source/core/svg/SVGClipPathElement.h
+++ b/Source/core/svg/SVGClipPathElement.h
@@ -24,7 +24,6 @@
 #include "SVGNames.h"
 #include "core/svg/SVGAnimatedBoolean.h"
 #include "core/svg/SVGAnimatedEnumeration.h"
-#include "core/svg/SVGExternalResourcesRequired.h"
 #include "core/svg/SVGGraphicsElement.h"
 #include "core/svg/SVGUnitTypes.h"
 
@@ -32,8 +31,7 @@ namespace WebCore {
 
 class RenderObject;
 
-class SVGClipPathElement FINAL : public SVGGraphicsElement,
-                                 public SVGExternalResourcesRequired {
+class SVGClipPathElement FINAL : public SVGGraphicsElement {
 public:
     static PassRefPtr<SVGClipPathElement> create(const QualifiedName&, Document&);
 
@@ -52,7 +50,6 @@ private:
 
     BEGIN_DECLARE_ANIMATED_PROPERTIES(SVGClipPathElement)
         DECLARE_ANIMATED_ENUMERATION(ClipPathUnits, clipPathUnits, SVGUnitTypes::SVGUnitType)
-        DECLARE_ANIMATED_BOOLEAN(ExternalResourcesRequired, externalResourcesRequired)
     END_DECLARE_ANIMATED_PROPERTIES
 };