Implement DOMQuad of geometry interfaces.

Source/core/dom/DOMPoint.h

Index: Source/core/dom/DOMPoint.h
diff --git a/Source/core/dom/DOMPoint.h b/Source/core/dom/DOMPoint.h
index 11d53ebacc7cdaf8e064d141cd785c4d116a7abb..c3c662767d547ce0e55e7d1c615a9aa5a112ec0a 100644
--- a/Source/core/dom/DOMPoint.h
+++ b/Source/core/dom/DOMPoint.h
@@ -10,13 +10,13 @@
 
 namespace blink {
 
-class DOMPoint FINAL : public DOMPointReadOnly {
+class DOMPoint : public DOMPointReadOnly {
 public:
     static DOMPoint* create(const Dictionary&);
     static DOMPoint* create(double x, double y, double z = 0, double w = 1);
 
-    void setX(double x) { m_x = x; }
-    void setY(double y) { m_y = y; }
+    virtual void setX(double x) { m_x = x; }
+    virtual void setY(double y) { m_y = y; }
     void setZ(double z) { m_z = z; }
     void setW(double w) { m_w = w; }