Remove support for the externalResourcesRequired attribute.

Source/core/svg/SVGLineElement.h

Index: Source/core/svg/SVGLineElement.h
diff --git a/Source/core/svg/SVGLineElement.h b/Source/core/svg/SVGLineElement.h
index ad09477246357f4ad0a6b162988dd3d1bcb5e979..dfe1cbcbce03b87036c1229e2135d4342ac376c8 100644
--- a/Source/core/svg/SVGLineElement.h
+++ b/Source/core/svg/SVGLineElement.h
@@ -24,13 +24,11 @@
 #include "SVGNames.h"
 #include "core/svg/SVGAnimatedBoolean.h"
 #include "core/svg/SVGAnimatedLength.h"
-#include "core/svg/SVGExternalResourcesRequired.h"
 #include "core/svg/SVGGraphicsElement.h"
 
 namespace WebCore {
 
-class SVGLineElement FINAL : public SVGGraphicsElement,
-                             public SVGExternalResourcesRequired {
+class SVGLineElement FINAL : public SVGGraphicsElement {
 public:
     static PassRefPtr<SVGLineElement> create(const QualifiedName&, Document&);
 
@@ -53,7 +51,6 @@ private:
         DECLARE_ANIMATED_LENGTH(Y1, y1)
         DECLARE_ANIMATED_LENGTH(X2, x2)
         DECLARE_ANIMATED_LENGTH(Y2, y2)
-        DECLARE_ANIMATED_BOOLEAN(ExternalResourcesRequired, externalResourcesRequired)
     END_DECLARE_ANIMATED_PROPERTIES
 };