Make classes and structures in core/html fast-allocated.

Source/core/html/imports/HTMLImport.h

Index: Source/core/html/imports/HTMLImport.h
diff --git a/Source/core/html/imports/HTMLImport.h b/Source/core/html/imports/HTMLImport.h
index 9cde31d6b05597742621e6ce83f391a239c4eed2..af08d6d87fda0fb0a9681d811deb4cb32d59a8b5 100644
--- a/Source/core/html/imports/HTMLImport.h
+++ b/Source/core/html/imports/HTMLImport.h
@@ -33,6 +33,7 @@
 
 #include "core/html/imports/HTMLImportState.h"
 #include "platform/heap/Handle.h"
+#include "wtf/Allocator.h"
 #include "wtf/TreeNode.h"
 
 namespace blink {
@@ -91,6 +92,7 @@ class HTMLImportLoader;
 // The superclass of HTMLImportTreeRoot and HTMLImportChild
 // This represents the import tree data structure.
 class HTMLImport : public NoBaseWillBeGarbageCollectedFinalized<HTMLImport>, public TreeNode<HTMLImport> {
+    WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED(HTMLImport);
 public:
     enum SyncMode {
         Sync  = 0,