Change ArrayBuffer API and implementation to use embedder-provided allocator.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 074d8dc59ddf6d12569904bcf9bc4ca227ee724f..a1f465f400c552f1d9e1209c28f8739b8eb2bb8e 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -663,7 +663,8 @@ static void ArrayBufferWeakCallback(v8::Isolate* external_isolate,
         isolate, array_buffer->byte_length());
     isolate->heap()->AdjustAmountOfExternalAllocatedMemory(
         -static_cast<intptr_t>(allocated_length));
-    free(data);
+    CHECK(V8::ArrayBufferAllocator() != NULL);
+    V8::ArrayBufferAllocator()->Free(data);
   }
   object->Dispose(external_isolate);
 }
@@ -699,8 +700,9 @@ bool Runtime::SetupArrayBufferAllocatingData(
     Handle<JSArrayBuffer> array_buffer,
     size_t allocated_length) {
   void* data;
+  CHECK(V8::ArrayBufferAllocator() != NULL);
   if (allocated_length != 0) {
-    data = malloc(allocated_length);
+    data = V8::ArrayBufferAllocator()->Allocate(allocated_length);
     if (data == NULL) return false;
     memset(data, 0, allocated_length);
   } else {