perf($rootScope): do not mark $watchCollectionInterceptor as $stateful

Author: jbedard

src/ng/rootScope.js

@@ -581,8 +581,6 @@ function $RootScopeProvider() {
        *    de-registration function is executed, the internal watch operation is terminated.
        */
       $watchCollection: function(obj, listener) {
-        $watchCollectionInterceptor.$stateful = true;
-
         var self = this;
         // the current value, updated on each dirty-check run
         var newValue;