Object.unobserve(obj, callback) now throws a TypeError when callback is not a function.

Review URL: https://codereview.chromium.org/11293248
Patch from Rafael Weinstein <rafaelw@chromium.org>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12950 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/object-observe.js

@@ -100,6 +100,8 @@ function ObjectObserve(object, callback) {
 function ObjectUnobserve(object, callback) {
   if (!IS_SPEC_OBJECT(object))
     throw MakeTypeError("observe_non_object", ["unobserve"]);
+  if (!IS_SPEC_FUNCTION(callback))
+    throw MakeTypeError("observe_non_function", ["unobserve"]);
 
   var objectInfo = objectInfoMap.get(object);
   if (IS_UNDEFINED(objectInfo))

test/mjsunit/harmony/object-observe.js

@@ -100,6 +100,7 @@ assertThrows(function() { Object.observe(obj, frozenFunction); }, TypeError);
 
 // Object.unobserve
 assertThrows(function() { Object.unobserve(4, observer.callback); }, TypeError);
+assertThrows(function() { Object.unobserve(obj, nonFunction); }, TypeError);
 
 // Object.getNotifier
 var notifier = Object.getNotifier(obj);