title: how to click ion-tabs when use protractor for e2e test
body: <p>I tried lots of ways but still have problem with that.
  This is my tabs.html</p>
  
  <pre><code>&lt;ion-tab class="tab1" [root]="tab1Root" tabTitle="Forum"    tabIcon="home"&gt;&lt;/ion-tab&gt;
  &lt;ion-tab class="tab2" [root]="tab2Root" tabTitle="Chat"     tabIcon="information-circle"&gt;&lt;/ion-tab&gt;
  &lt;ion-tab class="tab3" [root]="tab3Root" tabTitle="MyOLLE"   tabIcon="contacts"&gt;&lt;/ion-tab&gt;
  </code></pre>
  
  <p>This is my 1st tabs.e2e-spec.ts</p>
  
  <pre><code>var chat = element(by.tagName('ion-tab[tabTitle="Chat"]')).getWebElement();
  browser.actions().mouseMove(chat).click().perform();
  browser.sleep(6000);
  </code></pre>
  
  <p>The problem of above code is that it actually didn't go to the chat page when runing the test. </p>
  
  <p>My 2nd test</p>
  
  <pre><code>var chat = element(by.tagName('ion-tab[tabTitle="Chat"]'));
  chat.click();
  </code></pre>
  
  <p>This will tell me  </p>
  
  <blockquote>
    <p>Failed: element not visible</p>
  </blockquote>
  
  <p>Can anyone tell me how can I click the tab or how can I redirect to the page I want?</p>