[import] Cleanup: get rid of ad-hoc state machine.

Source/core/html/HTMLImportChild.h

Index: Source/core/html/HTMLImportChild.h
diff --git a/Source/core/html/HTMLImportChild.h b/Source/core/html/HTMLImportChild.h
index 28c790868905d98c52bcaa1fe6a6eb3a0f3e212d..d05cf238b9b40973875fb894e9cafcd566379226 100644
--- a/Source/core/html/HTMLImportChild.h
+++ b/Source/core/html/HTMLImportChild.h
@@ -72,9 +72,12 @@ public:
     virtual bool isDone() const OVERRIDE;
     virtual bool hasLoader() const OVERRIDE;
     virtual bool ownsLoader() const OVERRIDE;
-    virtual void didUnblockFromCreatingDocument() OVERRIDE;
-    virtual void didBecomeReady() OVERRIDE;
     virtual CustomElementMicrotaskImportStep* customElementMicrotaskStep() const OVERRIDE FINAL { return m_customElementMicrotaskStep; }
+    virtual void stateDidChange() OVERRIDE;
+
+#if !defined(NDEBUG)
+    virtual void showThis() OVERRIDE;
+#endif
 
     void addClient(HTMLImportChildClient*);
     void removeClient(HTMLImportChildClient*);