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

Source/core/html/track/vtt/VTTCue.h

Index: Source/core/html/track/vtt/VTTCue.h
diff --git a/Source/core/html/track/vtt/VTTCue.h b/Source/core/html/track/vtt/VTTCue.h
index 2bdde591ef3dfe9a701d176910c45b9d0c2bb06e..184994467d4fdc321f5f84e22f372f02719b4329 100644
--- a/Source/core/html/track/vtt/VTTCue.h
+++ b/Source/core/html/track/vtt/VTTCue.h
@@ -32,6 +32,7 @@
 
 #include "core/html/track/TextTrackCue.h"
 #include "platform/heap/Handle.h"
+#include "wtf/Allocator.h"
 
 namespace blink {
 
@@ -42,6 +43,7 @@ class VTTCue;
 class VTTScanner;
 
 struct VTTDisplayParameters {
+    STACK_ALLOCATED();
     VTTDisplayParameters();
 
     FloatPoint position;