[es6] Reintroduce the instanceof operator in the backends.

test/mjsunit/messages.js

Index: test/mjsunit/messages.js
diff --git a/test/mjsunit/messages.js b/test/mjsunit/messages.js
index 8796d05f16e5be3afadc562c64fce372253ca670..d40994d8490cca9943f028198b51ad13a7027c34 100644
--- a/test/mjsunit/messages.js
+++ b/test/mjsunit/messages.js
@@ -147,7 +147,12 @@ test(function() {
 }, "Method Set.prototype.add called on incompatible receiver [object Array]",
 TypeError);
 
-// kInstanceofFunctionExpected
+// kNonCallableInInstanceOfCheck
+test(function() {
+  1 instanceof {};
+}, "Right-hand side of 'instanceof' is not callable", TypeError);
+
+// kNonObjectInInstanceOfCheck
 test(function() {
   1 instanceof 1;
 }, "Right-hand side of 'instanceof' is not an object", TypeError);