Fix fast array literals to ignore prototype chain.

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 28c5304a41ec23ce8a1b4783d394d6717b9d0c09..c4f12f0a7c387a7fe858bb58e90a70391aefe9e2 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -4280,9 +4280,10 @@ void LCodeGen::EmitDeepCopy(Handle<JSObject> object,
         __ movq(FieldOperand(result, total_offset), rcx);
       }
     } else if (elements->IsFixedArray()) {
+      Handle<FixedArray> fast_elements = Handle<FixedArray>::cast(elements);
       for (int i = 0; i < elements_length; i++) {
         int total_offset = elements_offset + FixedArray::OffsetOfElementAt(i);
-        Handle<Object> value = JSObject::GetElement(object, i);
+        Handle<Object> value(fast_elements->get(i));
         if (value->IsJSObject()) {
           Handle<JSObject> value_object = Handle<JSObject>::cast(value);
           __ lea(rcx, Operand(result, *offset));