(Heap)TerminatedArrayBuilders are stack allocated.

third_party/WebKit/Source/platform/heap/HeapTerminatedArray.h

Index: third_party/WebKit/Source/platform/heap/HeapTerminatedArray.h
diff --git a/third_party/WebKit/Source/platform/heap/HeapTerminatedArray.h b/third_party/WebKit/Source/platform/heap/HeapTerminatedArray.h
index 46685066ec00120d114320cb1e41bbd01fc7cbd9..926fb539166841ffb0540f98d2e684a63b3d326c 100644
--- a/third_party/WebKit/Source/platform/heap/HeapTerminatedArray.h
+++ b/third_party/WebKit/Source/platform/heap/HeapTerminatedArray.h
@@ -27,13 +27,13 @@ public:
 
 private:
     // Allocator describes how HeapTerminatedArrayBuilder should create new intances
-    // of TerminateArray and manage their lifetimes.
+    // of HeapTerminatedArray and manage their lifetimes.
     struct Allocator final {
         STATIC_ONLY(Allocator);
-        typedef HeapTerminatedArray* PassPtr;
-        typedef HeapTerminatedArray* Ptr;
+        using PassPtr = HeapTerminatedArray*;
+        using Ptr = Member<HeapTerminatedArray>;
 
-        static PassPtr release(Ptr ptr)
+        static PassPtr release(Ptr& ptr)
         {
             return ptr;
         }