title: how to pass data from parent page to webview page in flutter?
body: <p>i want to pass a String data to a webview page, is it possible to do it in flutter? because i know how to do it using html and javascript via  contentWindow.postMessage() but i don't know how to implement it in flutter, thanks.</p>
  <p>This is my code in flutter to show the webview</p>
  <pre><code>Container(
                         height:500,
                          child: EasyWebView(
                              onLoaded: () {
                                print('loaded');
                              },
                              src: webviewsrc,
                              ),
                        ), 
  </code></pre>