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 0b0baec5ec7598afc55e58bc1483d3500dbf2845..66e85032d5d355082594491ea035e9c6f23ee9ff 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(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
 };