fix(doc): example was referring to non existent CSS

Author: mhevery

src/directives.js

@@ -623,25 +623,25 @@ function classDirective(name, selector) {
  * @example
    <doc:example>
      <doc:source>
-      <input type="button" value="set" ng:click="myVar='ng-input-indicator-wait'">
+      <input type="button" value="set" ng:click="myVar='ng-invalid'">
       <input type="button" value="clear" ng:click="myVar=''">
       <br>
       <span ng:class="myVar">Sample Text &nbsp;&nbsp;&nbsp;&nbsp;</span>
      </doc:source>
      <doc:scenario>
        it('should check ng:class', function() {
          expect(element('.doc-example-live span').prop('className')).not().
-           toMatch(/ng-input-indicator-wait/);
+           toMatch(/ng-invalid/);
 
          using('.doc-example-live').element(':button:first').click();
 
          expect(element('.doc-example-live span').prop('className')).
-           toMatch(/ng-input-indicator-wait/);
+           toMatch(/ng-invalid/);
 
          using('.doc-example-live').element(':button:last').click();
 
          expect(element('.doc-example-live span').prop('className')).not().
-           toMatch(/ng-input-indicator-wait/);
+           toMatch(/ng-invalid/);
        });
      </doc:scenario>
    </doc:example>
@@ -670,7 +670,7 @@ var ngClassDirective = classDirective('', true);
         <ol ng:init="names=['John', 'Mary', 'Cate', 'Suz']">
           <li ng:repeat="name in names">
            <span ng:class-odd="'ng-format-negative'"
-                 ng:class-even="'ng-input-indicator-wait'">
+                 ng:class-even="'ng-invalid'">
              {{name}} &nbsp; &nbsp; &nbsp;
            </span>
           </li>
@@ -681,7 +681,7 @@ var ngClassDirective = classDirective('', true);
          expect(element('.doc-example-live li:first span').prop('className')).
            toMatch(/ng-format-negative/);
          expect(element('.doc-example-live li:last span').prop('className')).
-           toMatch(/ng-input-indicator-wait/);
+           toMatch(/ng-invalid/);
        });
      </doc:scenario>
    </doc:example>