title: HTML5 pattern doesn't accept after one invalid entry
body: <p>I am using html5 pattern in an angularJS app, after the page load it works fine if i enter valid inputs, and if i once enter an invalid input it notifies the error, but after that it won't accept any value. It shows error on both valid and invalid inputs.</p>
  
  <p>Following is the code i am using. </p>
  
  <pre><code>&lt;div class="col-md-6 userform-leftspace"&gt;
      &lt;div class="form-group  madotory-border"&gt;
          &lt;input type="text" id="regular1" class="form-control" ng-model="systolicBp" pattern="/[0-9]{1,2,3}/" oninvalid="this.setCustomValidity('Please enter a valid reading')" required&gt;
          &lt;label for="regular1"&gt;Systolic Bp&lt;/label&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>Please have a look and help me solve this issue. Thanks</p>