Add a WebDocument::watchCssSelectors(selectors)

Source/core/dom/ElementRareData.h

Index: Source/core/dom/ElementRareData.h
diff --git a/Source/core/dom/ElementRareData.h b/Source/core/dom/ElementRareData.h
index dcc8564febd099d6352699f0d99d1d160897d916..1cf550cc0f9d669063a5194786c739a52bb3b71b 100644
--- a/Source/core/dom/ElementRareData.h
+++ b/Source/core/dom/ElementRareData.h
@@ -95,6 +95,9 @@ public:
     unsigned childIndex() const { return m_childIndex; }
     void setChildIndex(unsigned index) { m_childIndex = index; }
 
+    bool renderStyleWatchedSelectorsRepresentedInSelectorWatch() const { return m_renderStyleWatchedSelectorsRepresentedInSelectorWatch; }
+    void setRenderStyleWatchedSelectorsRepresentedInSelectorWatch(bool value) { m_renderStyleWatchedSelectorsRepresentedInSelectorWatch = value; }
+
     void clearShadow() { m_shadow = nullptr; }
     ElementShadow* shadow() const { return m_shadow.get(); }
     ElementShadow* ensureShadow()
@@ -167,6 +170,8 @@ private:
     unsigned m_childrenAffectedByForwardPositionalRules : 1;
     unsigned m_childrenAffectedByBackwardPositionalRules : 1;
 
+    unsigned m_renderStyleWatchedSelectorsRepresentedInSelectorWatch : 1;
+
     unsigned m_isInsideRegion : 1;
     RegionOversetState m_regionOversetState;
 
@@ -213,6 +218,7 @@ inline ElementRareData::ElementRareData(RenderObject* renderer)
     , m_childrenAffectedByDirectAdjacentRules(false)
     , m_childrenAffectedByForwardPositionalRules(false)
     , m_childrenAffectedByBackwardPositionalRules(false)
+    , m_renderStyleWatchedSelectorsRepresentedInSelectorWatch(false)
     , m_isInsideRegion(false)
     , m_regionOversetState(RegionUndefined)
     , m_minimumSizeForResizing(defaultMinimumSizeForResizing())