context.addHitRegion() is not working when using transform operation.

Source/core/html/canvas/CanvasRenderingContext2D.cpp

Index: Source/core/html/canvas/CanvasRenderingContext2D.cpp
diff --git a/Source/core/html/canvas/CanvasRenderingContext2D.cpp b/Source/core/html/canvas/CanvasRenderingContext2D.cpp
index 106c93fae5d436049d583a4aae50282c7165b75e..ba0fc0bd83a95fd6bc8ce227e180f643f84964ad 100644
--- a/Source/core/html/canvas/CanvasRenderingContext2D.cpp
+++ b/Source/core/html/canvas/CanvasRenderingContext2D.cpp
@@ -90,6 +90,7 @@ CanvasRenderingContext2D::CanvasRenderingContext2D(HTMLCanvasElement* canvas, co
     , m_contextRestorable(true)
     , m_storageMode(!attrs ? PersistentStorage : attrs->parsedStorage())
     , m_tryRestoreContextAttemptCount(0)
+    , m_clipCount(0)
     , m_dispatchContextLostEventTimer(this, &CanvasRenderingContext2D::dispatchContextLostEvent)
     , m_dispatchContextRestoredEventTimer(this, &CanvasRenderingContext2D::dispatchContextRestoredEvent)
     , m_tryRestoreContextEventTimer(this, &CanvasRenderingContext2D::tryRestoreContextEvent)
@@ -231,6 +232,7 @@ void CanvasRenderingContext2D::reset()
     m_stateStack.resize(1);
     m_stateStack.first() = adoptPtrWillBeNoop(new State());
     m_path.clear();
+    m_clipCount = 0;
     validateStateStack();
 }
 
@@ -372,6 +374,8 @@ void CanvasRenderingContext2D::realizeSaves()
 void CanvasRenderingContext2D::restore()
 {
     validateStateStack();
+    if (isClipMode())
+        --m_clipCount;

[Justin Novosad, 2014/07/02 15:12:31]

I don't think this is correct. There could be multiple clips on the same state
stack level.  There could also be 0 clips (this clip may come from a higher a
higher state stack level).
In order to restore properly, I think you need to save the the clipCount in the
state stack rather than in CanvasRenderingContext2D.

     if (state().m_unrealizedSaveCount) {
         // We never realized the save, so just record that it was unnecessary.
         --m_stateStack.last()->m_unrealizedSaveCount;
@@ -1096,6 +1100,7 @@ void CanvasRenderingContext2D::clipInternal(const Path& path, const String& wind
 
     realizeSaves();
     c->canvasClip(path, parseWinding(windingRuleString));
+    ++m_clipCount;
 }
 
 void CanvasRenderingContext2D::clip(const String& windingRuleString)
@@ -2385,7 +2390,7 @@ void CanvasRenderingContext2D::addHitRegion(const Dictionary& options, Exception
     Path specifiedPath = m_path;
     specifiedPath.transform(state().m_transform);
 
-    if (context->isClipMode()) {
+    if (isClipMode()) {
         // FIXME: The hit regions should take clipping region into account.
         // However, we have no way to get the region from canvas state stack by now.
         // See http://crbug.com/387057