Revert of Remove SIMD.js from V8.

src/factory.h

Index: src/factory.h
diff --git a/src/factory.h b/src/factory.h
index 01823a38fb62b6a0ee47c2f9774c545090c7fff4..85abc3efe0c94835bbaff5063e2eb95b5acdf90b 100644
--- a/src/factory.h
+++ b/src/factory.h
@@ -469,6 +469,12 @@
   Handle<HeapNumber> NewHeapNumber(MutableMode mode,
                                    PretenureFlag pretenure = NOT_TENURED);
 
+#define SIMD128_NEW_DECL(TYPE, Type, type, lane_count, lane_type) \
+  Handle<Type> New##Type(lane_type lanes[lane_count],             \
+                         PretenureFlag pretenure = NOT_TENURED);
+  SIMD128_TYPES(SIMD128_NEW_DECL)
+#undef SIMD128_NEW_DECL
+
   Handle<JSWeakMap> NewJSWeakMap();
 
   Handle<JSObject> NewArgumentsObject(Handle<JSFunction> callee, int length);