Automate Fullscreen web-platform-tests using wpt_automation

third_party/WebKit/LayoutTests/imported/wpt_automation/fullscreen/auto-click.js

+(function() {
+
+function click(button) {
+  var rect = button.getBoundingClientRect();
+  eventSender.mouseMoveTo(rect.left, rect.top);
+  eventSender.mouseDown();
+  eventSender.mouseUp();
+}
+
+var observer = new MutationObserver(mutations => {
+  for (var mutation of mutations) {
+    for (var node of mutation.addedNodes) {
+      if (node.localName == 'button')
+        click(node);
+      else if (node.localName == 'iframe')
+        observe(node.contentDocument);
+    }
+  }
+});
+
+function observe(target) {
+  observer.observe(target, { childList: true, subtree: true });
+}
+
+// Handle what's already in the document.
+for (var button of document.getElementsByTagName('button')) {
+  click(button);
+}
+for (var iframe of document.getElementsByTagName('iframe')) {
+  observe(iframe.contentDocument);
+}
+
+// Observe future changes.
+observe(document);
+
+})();