feat(autocomplete): support readonly attribute

Fixes #5507

Closes #7107

src/components/autocomplete/autocomplete.spec.js

@@ -119,6 +119,56 @@ describe('<md-autocomplete>', function() {
       element.remove();
     }));
 
+    it('should allow allow using ng-readonly', inject(function() {
+      var scope = createScope(null, {inputId: 'custom-input-id'});
+      var template = '\
+          <md-autocomplete\
+              md-input-id="{{inputId}}"\
+              md-selected-item="selectedItem"\
+              md-search-text="searchText"\
+              md-items="item in match(searchText)"\
+              md-item-text="item.display"\
+              placeholder="placeholder"\
+              ng-readonly="readonly">\
+            <span md-highlight-text="searchText">{{item.display}}</span>\
+          </md-autocomplete>';
+      var element = compile(template, scope);
+      var input = element.find('input');
+
+      scope.readonly = true;
+      scope.$digest();
+
+      expect(input.attr('readonly')).toBe('readonly');
+
+      scope.readonly = false;
+      scope.$digest();
+
+      expect(input.attr('readonly')).toBeUndefined();
+
+      element.remove();
+    }));
+
+    it('should allow allow using an empty readonly attribute', inject(function() {
+      var scope = createScope(null, {inputId: 'custom-input-id'});
+      var template = '\
+          <md-autocomplete\
+              md-input-id="{{inputId}}"\
+              md-selected-item="selectedItem"\
+              md-search-text="searchText"\
+              md-items="item in match(searchText)"\
+              md-item-text="item.display"\
+              placeholder="placeholder"\
+              readonly>\
+            <span md-highlight-text="searchText">{{item.display}}</span>\
+          </md-autocomplete>';
+      var element = compile(template, scope);
+      var input = element.find('input');
+
+      expect(input.attr('readonly')).toBe('readonly');
+
+      element.remove();
+    }));
+
     it('should allow you to set an input id with floating label', inject(function() {
       var scope = createScope(null, {inputId: 'custom-input-id'});
       var template = '\

src/components/autocomplete/js/autocompleteController.js

@@ -36,6 +36,7 @@ function MdAutocompleteCtrl ($scope, $element, $mdUtil, $mdConstant, $mdTheming,
   ctrl.id         = $mdUtil.nextUid();
   ctrl.isDisabled = null;
   ctrl.isRequired = null;
+  ctrl.isReadonly = null;
   ctrl.hasNotFound = false;
 
   //-- public methods
@@ -166,6 +167,7 @@ function MdAutocompleteCtrl ($scope, $element, $mdUtil, $mdConstant, $mdTheming,
     var wait = parseInt($scope.delay, 10) || 0;
     $attrs.$observe('disabled', function (value) { ctrl.isDisabled = $mdUtil.parseAttributeBoolean(value, false); });
     $attrs.$observe('required', function (value) { ctrl.isRequired = $mdUtil.parseAttributeBoolean(value, false); });
+    $attrs.$observe('readonly', function (value) { ctrl.isReadonly = $mdUtil.parseAttributeBoolean(value, false); });
     $scope.$watch('searchText', wait ? $mdUtil.debounce(handleSearchText, wait) : handleSearchText);
     $scope.$watch('selectedItem', selectedItemChange);
     angular.element($window).on('resize', positionDropdown);

src/components/autocomplete/js/autocompleteDirective.js

@@ -237,6 +237,7 @@ function MdAutocomplete () {
                   name="{{inputName}}"\
                   autocomplete="off"\
                   ng-required="$mdAutocompleteCtrl.isRequired"\
+                  ng-readonly="$mdAutocompleteCtrl.isReadonly"\
                   ng-minlength="inputMinlength"\
                   ng-maxlength="inputMaxlength"\
                   ng-disabled="$mdAutocompleteCtrl.isDisabled"\
@@ -263,6 +264,7 @@ function MdAutocomplete () {
                 autocomplete="off"\
                 ng-required="$mdAutocompleteCtrl.isRequired"\
                 ng-disabled="$mdAutocompleteCtrl.isDisabled"\
+                ng-readonly="$mdAutocompleteCtrl.isReadonly"\
                 ng-model="$mdAutocompleteCtrl.scope.searchText"\
                 ng-keydown="$mdAutocompleteCtrl.keydown($event)"\
                 ng-blur="$mdAutocompleteCtrl.blur()"\