fixed visualizer click not working due to find element problem

With introduction of Tidy one-to-one mapping beetwean actual and visualizer html xpathes
disappeared. Overcome this by generating custom attribute.

Author: Vasyl Vavrychuk

src/webdriver/extension_qt/web_view_visualizer.cc

@@ -21,6 +21,11 @@ QWebViewVisualizerSourceCommand::QWebViewVisualizerSourceCommand(QWebViewCmdExec
 void QWebViewVisualizerSourceCommand::Execute(std::string* source, Error** error) {
     // Convert DOM tree to valid XML.
     const char* kSource =
+        "var elements = document.getElementsByTagName('*');\n"
+        "for (var index = 0; index < elements.length; index++) {\n"
+        "  var element = elements[index];\n"
+        "  element.setAttribute('data-viz-id', index);\n"
+        "}\n"
         "var root = document.documentElement.cloneNode(true);\n"
         "var elements = root.getElementsByTagName('script');\n"
         "for (var index = 0; index < elements.length; index++) {\n"

web/webdriver-app.js

@@ -73,6 +73,9 @@ function _getXPath(node, path) {
 }
 
 function getXPath(node) {
+  if (node.hasAttribute('data-viz-id'))
+    return '//*[@data-viz-id=' + node.getAttribute('data-viz-id') + "]";
+
   var path = _getXPath(node);
   return '/' + path.join('/');
 }