Simplify subtree (now subsequence) caching

Source/platform/graphics/paint/SubtreeRecorder.h

Index: Source/platform/graphics/paint/SubtreeRecorder.h
diff --git a/Source/platform/graphics/paint/SubtreeRecorder.h b/Source/platform/graphics/paint/SubtreeRecorder.h
index c27e71d967b86217cff7441049b769c6d22797b2..01ea9d2b7ed45cd7c7a15d1d63962aa140e11444 100644
--- a/Source/platform/graphics/paint/SubtreeRecorder.h
+++ b/Source/platform/graphics/paint/SubtreeRecorder.h
@@ -17,19 +17,14 @@ class GraphicsContext;
 // for the paint phase.
 class PLATFORM_EXPORT SubtreeRecorder {
 public:
-    SubtreeRecorder(GraphicsContext&, const DisplayItemClientWrapper&, int paintPhase);
-    ~SubtreeRecorder();
+    static bool useCachedSubtreeIfPossible(GraphicsContext&, const DisplayItemClientWrapper&);
 
-    bool canUseCache() const;
+    SubtreeRecorder(GraphicsContext&, const DisplayItemClientWrapper&);
+    ~SubtreeRecorder();
 
 private:
     DisplayItemList* m_displayItemList;
     DisplayItemClientWrapper m_client;
-    const int m_paintPhase;
-    bool m_canUseCache;
-#if ENABLE(ASSERT)
-    mutable bool m_checkedCanUseCache;
-#endif
 };
 
 } // namespace blink