Serialize original node when dragging a link instead of synthesizing HTML.

third_party/WebKit/LayoutTests/editing/pasteboard/drop-link.html

 <script>
 if (window.testRunner)
      testRunner.dumpEditingCallbacks();
 </script>
 <div>This test checks that links dragged into editable regions preserve their title and URL.</div>
 
 <div contenteditable="true" id="destination">Hello</div>
 <div contenteditable="true" id="destination2">Goodbye</div>
 
 <div><a href="http://apple.com" id="grabme">This is a link</a></div>
@@ skipping 39 matching lines @@
     eventSender.mouseDown();
     // Wait a moment so that the mouseDown will kick off a drag instead of navigating to the link
     eventSender.leapForward(400);
 
     var destinationObject = document.getElementById(targetId);
     var x = destinationObject.offsetLeft + destinationObject.offsetWidth / 2;
     var y = destinationObject.offsetTop + destinationObject.offsetHeight / 2;
 
     eventSender.mouseMoveTo(x, y);
     eventSender.mouseUp();
+
+    // Clear id on the cloned link created from the drag and drop.
+    document.querySelector("a[id]").removeAttribute('id');
 }
 
 function verifier() {
     var anchorToDrag = document.getElementById("grabme");
     var anchorToDrag2 = document.getElementById("grabme2");
 
     var passed = verifyLink('grabme', 0) && verifyLink('grabme2', 1);
 
     var anchors = document.getElementsByTagName("a");
     if (anchors.length != 2) {
@@ skipping 15 matching lines @@
     anchorParent.removeChild(anchorToDrag);
 
     var anchors = document.getElementsByTagName("a");
     if (!anchors[linkNumber]) {
         log("Link " + linkNumber + " not found");
         passed = false;
     } else {
         log("Link is " + anchors[linkNumber].href);
         var passed = true;
         if (anchors[linkNumber].href != originalTarget) {
-            log("Failure! Link targets differ");
+            log("Failure! Expected target: " + anchors[linkNumber].href + ", actual target: " + originalTarget);
             passed = false;
         }
         if (anchors[linkNumber].innerText != originalText) {
-            log("Failure! Link texts differ");
+            log("Failure! Expected text: " + anchors[linkNumber].innerText + ", actual text: " + originalText);
             passed = false;
         }
     }
     return passed;
 }
 
 runTest();
 </script>