feat(prompt): implement "required" flag for prompt dialogs (#10626)

Fixes #10135

Author: mdklab

src/components/dialog/demoBasicUsage/script.js

@@ -46,6 +46,7 @@ angular.module('dialogDemo1', ['ngMaterial'])
       .ariaLabel('Dog name')
       .initialValue('Buddy')
       .targetEvent(ev)
+      .required(true)
       .ok('Okay!')
       .cancel('I\'m a cat person');
 

src/components/dialog/dialog.js

@@ -598,7 +598,7 @@ function MdDialogProvider($$interimElementProvider) {
     })
     .addPreset('prompt', {
       methods: ['title', 'htmlContent', 'textContent', 'initialValue', 'content', 'placeholder', 'ariaLabel',
-          'ok', 'cancel', 'theme', 'css'],
+          'ok', 'cancel', 'theme', 'css', 'required'],
       options: advancedDialogOptions
     });
 
@@ -616,15 +616,16 @@ function MdDialogProvider($$interimElementProvider) {
         '    </div>',
         '    <md-input-container md-no-float ng-if="::dialog.$type == \'prompt\'" class="md-prompt-input-container">',
         '      <input ng-keypress="dialog.keypress($event)" md-autofocus ng-model="dialog.result" ' +
-        '             placeholder="{{::dialog.placeholder}}">',
+        '             placeholder="{{::dialog.placeholder}}" ng-required="dialog.required">',
         '    </md-input-container>',
         '  </md-dialog-content>',
         '  <md-dialog-actions>',
         '    <md-button ng-if="dialog.$type === \'confirm\' || dialog.$type === \'prompt\'"' +
         '               ng-click="dialog.abort()" class="md-primary md-cancel-button">',
         '      {{ dialog.cancel }}',
         '    </md-button>',
-        '    <md-button ng-click="dialog.hide()" class="md-primary md-confirm-button" md-autofocus="dialog.$type===\'alert\'">',
+        '    <md-button ng-click="dialog.hide()" class="md-primary md-confirm-button" md-autofocus="dialog.$type===\'alert\'"' +
+        '               ng-disabled="dialog.required && !dialog.result">',
         '      {{ dialog.ok }}',
         '    </md-button>',
         '  </md-dialog-actions>',