refactor(ionNavBackButton): make click handler use $ionicNgClick service

Closes #802

Author: ajoslin

js/ext/angular/src/directive/ionicNavBar.js

@@ -282,7 +282,7 @@ function($ionicViewService, $rootScope, $animate, $compile, $parse) {
  * </ion-nav-bar>
  * ```
  */
-.directive('ionNavBackButton', [function() {
+.directive('ionNavBackButton', ['$ionicNgClick', function($ionicNgClick) {
   return {
     restrict: 'E',
     require: '^ionNavBar',
@@ -292,8 +292,9 @@ function($ionicViewService, $rootScope, $animate, $compile, $parse) {
       '<button class="button back-button" ng-transclude>' +
       '</button>',
     link: function($scope, $element, $attr, navBarCtrl) {
+      $scope.$navBack = navBarCtrl.back;
       if (!$attr.ngClick) {
-        ionic.on('tap', navBarCtrl.back, $element[0]);
+        $ionicNgClick($scope, $element, '$navBack($event)');
       }
 
       //If the current viewstate does not allow a back button,

js/ext/angular/test/directive/ionicNavBackButton.unit.js

@@ -1,5 +1,5 @@
 describe('ionNavBackButton directive', function() {
-  beforeEach(module('ionic.ui.navBar'));
+  beforeEach(module('ionic'));
 
   function setup(attr, content) {
     var el;
@@ -53,19 +53,19 @@ describe('ionNavBackButton directive', function() {
     expect(el.children().eq(0)[0].tagName.toLowerCase()).toBe('b');
   });
 
-  it('should add onTap if ngClick isnt defined', function() {
-    spyOn(ionic, 'on');
+  it('should $navBack on click by default', function() {
     var el = setup();
-    expect(ionic.on).toHaveBeenCalledWith(
-      'tap',
-      el.controller('ionNavBar').back,
-      el[0]
-    );
+    el.scope().$navBack = jasmine.createSpy('$navBack');
+    el.triggerHandler('click');
+    expect(el.scope().$navBack).toHaveBeenCalled();
   });
 
-  it('should not add onTap if ngClick is defined', function() {
-    spyOn(ionic, 'on');
+  it('should do ngClick expression if defined', function() {
     var el = setup('ng-click="doSomething()"');
-    expect(ionic.on).not.toHaveBeenCalled();
+    el.scope().$navBack = jasmine.createSpy('$navBack');
+    el.scope().doSomething = jasmine.createSpy('doSomething');
+    el.triggerHandler('click');
+    expect(el.scope().$navBack).not.toHaveBeenCalled();
+    expect(el.scope().doSomething).toHaveBeenCalled();
   });
 });