DevTools: Fix Element.positionAt

Source/devtools/front_end/platform/DOMExtension.js

Index: Source/devtools/front_end/platform/DOMExtension.js
diff --git a/Source/devtools/front_end/platform/DOMExtension.js b/Source/devtools/front_end/platform/DOMExtension.js
index 842defdfcf4d5493dafc27139498489873df58b9..404ccf2d74e9fbd756dcded7be3531280f8c5826 100644
--- a/Source/devtools/front_end/platform/DOMExtension.js
+++ b/Source/devtools/front_end/platform/DOMExtension.js
@@ -160,6 +160,11 @@ Element.prototype.positionAt = function(x, y, relativeTo)
         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");
 }
 
 /**