Make classes and structures in core/style, core/plugins and core/streams fast-allocated.

Source/core/plugins/testing/DocumentFragmentPluginPlaceholder.h

Index: Source/core/plugins/testing/DocumentFragmentPluginPlaceholder.h
diff --git a/Source/core/plugins/testing/DocumentFragmentPluginPlaceholder.h b/Source/core/plugins/testing/DocumentFragmentPluginPlaceholder.h
index d89ac0dc4ef9fd06abec652ae333e1f1dc9f0121..aa7d0ffe19a155349e317c992f87117ebce8d8eb 100644
--- a/Source/core/plugins/testing/DocumentFragmentPluginPlaceholder.h
+++ b/Source/core/plugins/testing/DocumentFragmentPluginPlaceholder.h
@@ -13,8 +13,9 @@ namespace blink {
 
 // Populates plugin placeholder content with a document fragment.
 // Used for layout tests that contain a <template>.
-class DocumentFragmentPluginPlaceholder : public NoBaseWillBeGarbageCollected<DocumentFragmentPluginPlaceholder>, public PluginPlaceholder {
+class DocumentFragmentPluginPlaceholder final : public NoBaseWillBeGarbageCollected<DocumentFragmentPluginPlaceholder>, public PluginPlaceholder {
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(DocumentFragmentPluginPlaceholder);
+    WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED(DocumentFragmentPluginPlaceholder);
 public:
     static PassOwnPtrWillBeRawPtr<DocumentFragmentPluginPlaceholder> create(PassRefPtrWillBeRawPtr<DocumentFragment> fragment)
     {