title: not calling onNavigationStateChange when some link is clicked in WebView
body: <h3>Environment</h3>
  
  <ul>
  <li>react-native: 0.25.1  </li>
  <li>Device: iOS,iPhone6 Simulator  </li>
  <li>OS: Mac OS X El Capitan 10.11.4  </li>
  </ul>
  
  <h3>code snippet</h3>
  
  <ul>
  <li><p>not calling onNavigationStateChange when some link is clicked in WebView. Here is the code snippet:</p>
  
  <pre><code>_onNavigationStateChange(navState) {
          console.log('_onNavigationStateChangeevent:',navState);
      }
  render() {
      return(
          &lt;WebView
              style={{
                flex:1,
                marginTop:20
              }}
              ref={WEBVIEW_REF}
              source={{uri: 'https://www.tumblr.com/explore/text'}}
              scalesPageToFit={true}
              contentInset={{bottom:44}}
              onLoadStart={this._onLoadStart.bind(this)}
              onLoad={this._onLoadEnd.bind(this)}
              onNavigationStateChange={this._onNavigationStateChange.bind(this)}
              onShouldStartLoadWithRequest={this._onShouldStartLoadWithRequest}
              startInLoadingState={true}
              javaScriptEnabled={true}
              domStorageEnabled={true}
          /&gt;
      );
  }
  </code></pre></li>
  </ul>
  
  <h2><strong>screenshots</strong> where appropriate</h2>
  
  <p>detail:
  <a href="https://github.com/facebook/react-native/issues/7602" rel="nofollow noreferrer">https://github.com/facebook/react-native/issues/7602</a></p>
  
  <p><strong>How to know the navState if the onNavigationStateChange method is not called?</strong></p>