Speed-up 'new TypedArray(arrayLike)'.

include/v8.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2392 matching lines @@
    * V8::SetArrayBufferAllocator prior to creation of a first ArrayBuffer.
    *
    * This API is experimental and may change significantly.
    */
   class V8EXPORT Allocator { // NOLINT
    public:
     virtual ~Allocator() {}
 
     /**
      * Allocate |length| bytes. Return NULL if allocation is not successful.
+     * Memory should be initialized to zeroes.
      */
     virtual void* Allocate(size_t length) = 0;
+
+    /**
+     * Allocate |length| bytes. Return NULL if allocation is not successful.
+     * Memory does not have to be initialized.
+     */
+    virtual void* AllocateUninitialized(size_t length) {
+      // Override with call to |Allocate| for compatibility
+      // with legacy version.
+      return Allocate(length);
+    }
+
     /**
      * Free the memory pointed to |data|. That memory is guaranteed to be
      * previously allocated by |Allocate|.
      */
     virtual void Free(void* data) = 0;
   };
 
   /**
    * The contents of an |ArrayBuffer|. Externalization of |ArrayBuffer|
    * returns an instance of this class, populated, with a pointer to data
@@ skipping 4090 matching lines @@
 
 
 }  // namespace v8
 
 
 #undef V8EXPORT
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_