feat(autocomplete): support readonly attribute

Fixes #5507

Closes #7107

Author: devversion

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

@@ -230,6 +230,7 @@ function MdAutocomplete () {
                   name="{{inputName}}"\
                   autocomplete="off"\
                   ng-required="$mdAutocompleteCtrl.isRequired"\
+                  ng-readonly="$mdAutocompleteCtrl.isReadonly"\
                   ng-minlength="inputMinlength"\
                   ng-maxlength="inputMaxlength"\
                   ng-disabled="$mdAutocompleteCtrl.isDisabled"\
@@ -255,6 +256,7 @@ function MdAutocomplete () {
                 autocomplete="off"\
                 ng-required="$mdAutocompleteCtrl.isRequired"\
                 ng-disabled="$mdAutocompleteCtrl.isDisabled"\
+                ng-readonly="$mdAutocompleteCtrl.isReadonly"\
                 ng-model="$mdAutocompleteCtrl.scope.searchText"\
                 ng-keydown="$mdAutocompleteCtrl.keydown($event)"\
                 ng-blur="$mdAutocompleteCtrl.blur()"\