Remove forward declarations from Source/core/dom/custom

Source/core/dom/custom/CustomElementAsyncImportMicrotaskQueue.h

Index: Source/core/dom/custom/CustomElementAsyncImportMicrotaskQueue.h
diff --git a/Source/core/dom/custom/CustomElementAsyncImportMicrotaskQueue.h b/Source/core/dom/custom/CustomElementAsyncImportMicrotaskQueue.h
index 58dbe41f935bcf0fc6ba918e0d95f73048bf6a2d..c43ee5b43dfd0256d853b1bb85adf55461295a42 100644
--- a/Source/core/dom/custom/CustomElementAsyncImportMicrotaskQueue.h
+++ b/Source/core/dom/custom/CustomElementAsyncImportMicrotaskQueue.h
@@ -35,8 +35,6 @@
 
 namespace blink {
 
-class CustomElementMicrotaskImportStep;
-
 class CustomElementAsyncImportMicrotaskQueue : public CustomElementMicrotaskQueueBase {
 public:
     static PassRefPtrWillBeRawPtr<CustomElementAsyncImportMicrotaskQueue> create() { return adoptRefWillBeNoop(new CustomElementAsyncImportMicrotaskQueue()); }
@@ -48,5 +46,6 @@ private:
     virtual void doDispatch() OVERRIDE;
 };
 
-}
+} // namespace blink
+
 #endif // CustomElementAsyncImportMicrotaskQueue_h