DevTools: Fix Element.positionAt

Source/devtools/front_end/platform/DOMExtension.js

 /*
  * Copyright (C) 2007 Apple Inc.  All rights reserved.
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 142 matching lines @@
 
     if (typeof x === "number")
         this.style.setProperty("left", (shift.x + x) + "px");
     else
         this.style.removeProperty("left");
 
     if (typeof y === "number")
         this.style.setProperty("top", (shift.y + y) + "px");
     else
         this.style.removeProperty("top");
+
+    if (typeof x === "number" || typeof y === "number")
+        this.style.setProperty("position", "absolute");
+    else
+        this.style.removeProperty("position");
 }
 
 /**
  * @return {boolean}
  */
 Element.prototype.isScrolledToBottom = function()
 {
     // This code works only for 0-width border.
     // Both clientHeight and scrollHeight are rounded to integer values, so we tolerate
     // one pixel error.
@@ skipping 779 matching lines @@
     {
         window.removeEventListener("DOMContentLoaded", windowLoaded, false);
         callback();
     }
 
     if (document.readyState === "complete" || document.readyState === "interactive")
         callback();
     else
         window.addEventListener("DOMContentLoaded", windowLoaded, false);
 }