Remove some dead code in SVG "mixins"

third_party/WebKit/Source/core/svg/SVGTests.h

Index: third_party/WebKit/Source/core/svg/SVGTests.h
diff --git a/third_party/WebKit/Source/core/svg/SVGTests.h b/third_party/WebKit/Source/core/svg/SVGTests.h
index 2d83acc2bd99d8ab7d1bad7b09676c6ce505c5b9..097c160784c46dbb4f9d44ec1549666c9bc4d533 100644
--- a/third_party/WebKit/Source/core/svg/SVGTests.h
+++ b/third_party/WebKit/Source/core/svg/SVGTests.h
@@ -24,7 +24,6 @@
 #include "core/CoreExport.h"
 #include "core/svg/SVGStaticStringList.h"
 #include "platform/heap/Handle.h"
-#include "wtf/HashSet.h"
 
 namespace blink {
 
@@ -39,13 +38,10 @@ public:
     SVGStringListTearOff* requiredExtensions() { return m_requiredExtensions->tearOff(); }
     SVGStringListTearOff* systemLanguage() { return m_systemLanguage->tearOff(); }
 
-    bool isValid(Document&) const;
+    bool isValid() const;
 
-    bool parseAttribute(const QualifiedName&, const AtomicString&);
     bool isKnownAttribute(const QualifiedName&);
 
-    void addSupportedAttributes(HashSet<QualifiedName>&);
-
     DECLARE_VIRTUAL_TRACE();
 
 protected: