Revert of Tracking filter mutation via SVGElementProxy

third_party/WebKit/Source/core/style/FilterOperation.cpp

Index: third_party/WebKit/Source/core/style/FilterOperation.cpp
diff --git a/third_party/WebKit/Source/core/style/FilterOperation.cpp b/third_party/WebKit/Source/core/style/FilterOperation.cpp
index f72b6772bbe7e20daecd7910f0417521396756ce..6308d7038524d54066c603caa56efdd43355da27 100644
--- a/third_party/WebKit/Source/core/style/FilterOperation.cpp
+++ b/third_party/WebKit/Source/core/style/FilterOperation.cpp
@@ -25,7 +25,6 @@
 
 #include "core/style/FilterOperation.h"
 
-#include "core/svg/SVGElementProxy.h"
 #include "platform/LengthFunctions.h"
 #include "platform/animation/AnimationUtilities.h"
 #include "platform/graphics/filters/FEDropShadow.h"
@@ -45,7 +44,6 @@
 }
 
 DEFINE_TRACE(ReferenceFilterOperation) {
-  visitor->trace(m_elementProxy);
   visitor->trace(m_filter);
   FilterOperation::trace(visitor);
 }
@@ -55,26 +53,6 @@
   if (!lastEffect)
     return rect;
   return lastEffect->mapRect(rect);
-}
-
-ReferenceFilterOperation::ReferenceFilterOperation(
-    const String& url,
-    SVGElementProxy& elementProxy)
-    : FilterOperation(REFERENCE), m_url(url), m_elementProxy(&elementProxy) {}
-
-void ReferenceFilterOperation::addClient(SVGResourceClient* client) {
-  m_elementProxy->addClient(client);
-}
-
-void ReferenceFilterOperation::removeClient(SVGResourceClient* client) {
-  m_elementProxy->removeClient(client);
-}
-
-bool ReferenceFilterOperation::operator==(const FilterOperation& o) const {
-  if (!isSameType(o))
-    return false;
-  const ReferenceFilterOperation& other = toReferenceFilterOperation(o);
-  return m_url == other.m_url && m_elementProxy == other.m_elementProxy;
 }
 
 FilterOperation* BasicColorMatrixFilterOperation::blend(