Remove checking event.preventDefault and calling event.returnValue. Related to issue angular#4557. Worked with @bullwrinkle on this.

Author: shwei

src/ng/directive/form.js

@@ -465,8 +465,8 @@ var formDirectiveFactory = function(isNgForm) {
               // IE 9 is not affected because it doesn't fire a submit event and try to do a full
               // page reload if the form was destroyed by submission of the form via a click handler
               // on a button in the form. Looks like an IE9 specific bug.
-	      // 
-	      // Checking event.preventDefault and calling event.returnValue were removed. 
+              //
+              // Checking event.preventDefault and calling event.returnValue were removed.
               var handleFormSubmission = function(event) {
                 scope.$apply(function() {
                   controller.$commitViewValue();