Implement basic parts of hit regions on canvas2d.

Source/core/testing/Internals.h

Index: Source/core/testing/Internals.h
diff --git a/Source/core/testing/Internals.h b/Source/core/testing/Internals.h
index bcf97a88c18039b4565603dc194ae24e80c8d85e..15abc17ebc176b16ed37038036bc5365a70d1a33 100644
--- a/Source/core/testing/Internals.h
+++ b/Source/core/testing/Internals.h
@@ -42,6 +42,7 @@
 
 namespace WebCore {
 
+class CanvasRenderingContext2D;
 class ClientRect;
 class ClientRectList;
 class DOMPoint;
@@ -323,6 +324,8 @@ public:
     // Test must call setNetworkStateNotifierTestOnly(true) before calling setNetworkConnectionInfo.
     void setNetworkConnectionInfo(const String&, ExceptionState&);
 
+    unsigned countHitRegions(CanvasRenderingContext2D*);
+
 private:
     explicit Internals(Document*);
     Document* contextDocument() const;