(Heap)TerminatedArrayBuilders are stack allocated.

third_party/WebKit/Source/wtf/TerminatedArray.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 #ifndef TerminatedArray_h
 #define TerminatedArray_h
 
 #include "wtf/Allocator.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/allocator/Partitions.h"
 
@@ skipping 56 matching lines @@
     }
 
     // Match Allocator semantics to be able to use OwnPtr<TerminatedArray>.
     void operator delete(void* p) { ::WTF::Partitions::fastFree(p); }
 
 private:
     // Allocator describes how TerminatedArrayBuilder should create new instances
     // of TerminateArray and manage their lifetimes.
     struct Allocator {
         STATIC_ONLY(Allocator);
-        typedef PassOwnPtr<TerminatedArray> PassPtr;
-        typedef OwnPtr<TerminatedArray> Ptr;
+        using PassPtr = PassOwnPtr<TerminatedArray>;
+        using Ptr = OwnPtr<TerminatedArray>;
 
         static PassPtr release(Ptr& ptr)
         {
             return ptr.release();
         }
 
         static PassPtr create(size_t capacity)
         {
             return adoptPtr(static_cast<TerminatedArray*>(WTF::Partitions::fastMalloc(capacity * sizeof(T), WTF_HEAP_PROFILER_TYPE_NAME(T))));
         }
 
         static PassPtr resize(Ptr ptr, size_t capacity)
         {
             return adoptPtr(static_cast<TerminatedArray*>(WTF::Partitions::fastRealloc(ptr.leakPtr(), capacity * sizeof(T), WTF_HEAP_PROFILER_TYPE_NAME(T))));
         }
     };
 
     // Prohibit construction. Allocator makes TerminatedArray instances for
     // TerminatedArrayBuilder by pointer casting.
     TerminatedArray();
 
     template<typename, template <typename> class> friend class TerminatedArrayBuilder;
 };
 
 } // namespace WTF
 
 using WTF::TerminatedArray;
 
 #endif // TerminatedArray_h