Add a WebDocument::watchCssSelectors(selectors)

Source/core/dom/Element.h

Index: Source/core/dom/Element.h
diff --git a/Source/core/dom/Element.h b/Source/core/dom/Element.h
index 9d1ad8343298f90e3eeeaf046391b1f56ad67460..9e8a3cf23a2fe0535ebf6b9ef03dcd67ec6f3055 100644
--- a/Source/core/dom/Element.h
+++ b/Source/core/dom/Element.h
@@ -751,6 +751,8 @@ private:
 
     virtual RenderStyle* virtualComputedStyle(PseudoId pseudoElementSpecifier = NOPSEUDO) { return computedStyle(pseudoElementSpecifier); }
 
+    void updateCallbackSelectors(RenderStyle* oldStyle, RenderStyle* newStyle);
+
     // cloneNode is private so that non-virtual cloneElementWithChildren and cloneElementWithoutChildren
     // are used instead.
     virtual PassRefPtr<Node> cloneNode(bool deep) OVERRIDE;