fix(dropdown): Fix $digest:inprog on dropdown dismissal

src/dropdown/dropdown.js

@@ -4,7 +4,7 @@ angular.module('ui.bootstrap.dropdown', [])
   openClass: 'open'
 })
 
-.service('dropdownService', ['$document', function($document) {
+.service('dropdownService', ['$document', '$rootScope', function($document, $rootScope) {
   var openScope = null;
 
   this.open = function( dropdownScope ) {
@@ -38,9 +38,11 @@ angular.module('ui.bootstrap.dropdown', [])
         return;
     }
 
-    openScope.$apply(function() {
-      openScope.isOpen = false;
-    });
+    openScope.isOpen = false;
+
+    if (!$rootScope.$$phase) {
+      openScope.$apply();
+    }
   };
 
   var escapeKeyBind = function( evt ) {

src/dropdown/test/dropdown.spec.js

@@ -166,6 +166,18 @@ describe('dropdownToggle', function() {
       clickDropdownToggle();
       expect(toggleEl.attr('aria-expanded')).toBe('false');
     });
+
+    // pr/issue 3274
+    it('should not raise $digest:inprog if dismissed during a digest cycle', function () {
+      clickDropdownToggle();
+      expect(element.hasClass('open')).toBe(true);
+
+      $rootScope.$apply(function () {
+        $document.click();
+      });
+
+      expect(element.hasClass('open')).toBe(false);
+    });
   });
 
   describe('integration with $location URL rewriting', function() {