Add a WebDocument::watchCssSelectors(selectors)

Source/core/css/resolver/StyleResolverState.h

Index: Source/core/css/resolver/StyleResolverState.h
diff --git a/Source/core/css/resolver/StyleResolverState.h b/Source/core/css/resolver/StyleResolverState.h
index f414c21963b950a852f7792f21f9c4d7a30c2c35..ef7d3d6b18db2d95337d9d29413fbe2e2eac439e 100644
--- a/Source/core/css/resolver/StyleResolverState.h
+++ b/Source/core/css/resolver/StyleResolverState.h
@@ -38,6 +38,7 @@ namespace WebCore {
 
 class FontDescription;
 class RenderRegion;
+class StyleRule;
 
 class StyleResolverState {
 WTF_MAKE_NONCOPYABLE(StyleResolverState);
@@ -68,6 +69,9 @@ public:
 
     const RenderRegion* regionForStyling() const { return m_regionForStyling; }
 
+    void setCurrentRule(StyleRule* currentRule) { m_currentRule = currentRule; }
+    const StyleRule* currentRule() const { return m_currentRule; }
+
     // FIXME: These are effectively side-channel "out parameters" for the various
     // map functions. When we map from CSS to style objects we use this state object
     // to track various meta-data about that mapping (e.g. if it's cache-able).
@@ -155,6 +159,8 @@ private:
     // a back-pointer to this object.
     CSSToStyleMap m_styleMap;
     Vector<AtomicString> m_contentAttrValues;
+
+    StyleRule* m_currentRule;
 };
 
 } // namespace WebCore