[DevTools] Account for synthetic events in deepElementFromPoint()

third_party/WebKit/Source/devtools/front_end/dom_extension/DOMExtension.js

Index: third_party/WebKit/Source/devtools/front_end/dom_extension/DOMExtension.js
diff --git a/third_party/WebKit/Source/devtools/front_end/dom_extension/DOMExtension.js b/third_party/WebKit/Source/devtools/front_end/dom_extension/DOMExtension.js
index f9d202ca5a5707aecd46a3361aceb160e9e89138..8f6733c0421cbc65a36ad422cd7bdb48365d237f 100644
--- a/third_party/WebKit/Source/devtools/front_end/dom_extension/DOMExtension.js
+++ b/third_party/WebKit/Source/devtools/front_end/dom_extension/DOMExtension.js
@@ -757,6 +757,9 @@ Node.prototype.setTextContentTruncatedIfNeeded = function(text, placeholder) {
  * @return {?Node}
  */
 Event.prototype.deepElementFromPoint = function() {
+  // Some synthetic events have zero coordinates which lead to a wrong element. Better return nothing in this case.
+  if (!this.which && !this.pageX && !this.pageY && !this.clientX && !this.clientY && !this.movementX && !this.movementY)
+    return null;
   var root = this.target && this.target.getComponentRoot();
   return root ? root.deepElementFromPoint(this.pageX, this.pageY) : null;
 };