title: WebViewJavascriptBridge not call again when dismissViewController
body: <p>when the view show the first time, the js event run normaly. than I use <code>presentViewController</code> to show the image which I click. after <code>dismissViewController</code> , back to the webView, click the image again,but the js callHandler not run. Here is my code.</p>
  
  <pre><code>// oc file code
  
  - (void)viewWillAppear:(BOOL)animated {
      [super viewWillAppear:animated];
      if (_bridge) { return; }
  
      _bridge = [WebViewJavascriptBridge bridgeForWebView:self.webView];
  
      [_bridge registerHandler:@"jsImagesList" handler:^(id data, WVJBResponseCallback responseCallback) {
          self.imageList = data;
      }];
  
      [_bridge registerHandler:@"openImageOnIndex" handler:^(id data, WVJBResponseCallback responseCallback) {
          [self openImageOnIndex:data];// use MWPhotoBrowser to show the image
      }];
  }
  
  // js file code
  
  function setupWebViewJavascriptBridge(callback) {
      // just copy from WebViewJavascriptBridge
  }
  
  setupWebViewJavascriptBridge(function(bridge) {
  
      var objs = document.getElementsByTagName("img");
      var images = [];
      for(var i=0;i&lt;objs.length;i++) {
          images.push(objs[i].src);
          objs[i].setAttribute('data-index',i);
          objs[i].onclick = function(){
  
              // just for test, let me know I can click the img
              document.body.style.backgroundColor = '#'+Math.floor(Math.random()*0xFFFFFF).toString(16);
  
              var di = this.getAttribute('data-index');
  
              // ----------- question -----------
              // first time it run, but when dismissViewController, it not run
              bridge.callHandler('openImageOnIndex', {'i': di}, function(response) {})
          }
      }
      bridge.callHandler('jsImagesList', images, function(response) {})
  })
  </code></pre>
  
  <p>how can I modify it, thank you very much !</p>