DevTools: fix offset condition in console viewport _selectedText and add tests

third_party/WebKit/Source/devtools/front_end/console/ConsoleViewport.js

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 448 matching lines @@
     }
 
     var chars = 0;
     var node = itemElement;
     while ((node = node.traverseNextNode(itemElement)) && node !== selectionNode) {
       if (node.nodeType !== Node.TEXT_NODE || node.parentElement.nodeName === 'STYLE' ||
           node.parentElement.nodeName === 'SCRIPT')
         continue;
       chars += Components.Linkifier.untruncatedNodeText(node).length;
     }
-    // If the selection offset is at the end of a link's ellipsis, use the untruncated length as offset.
+    // If the selected node text was truncated, treat any non-zero offset as the full length.
     var untruncatedContainerLength = Components.Linkifier.untruncatedNodeText(selectionNode).length;
-    if (offset === 1 && untruncatedContainerLength > offset)
+    if (offset > 0 && untruncatedContainerLength !== selectionNode.textContent.length)
       offset = untruncatedContainerLength;
     return chars + offset;
   }
 
   /**
    * @param {!Event} event
    */
   _onScroll(event) {
     this.refresh();
   }
@@ skipping 124 matching lines @@
 Console.ConsoleViewportElement.prototype = {
   willHide() {},
 
   wasShown() {},
 
   /**
    * @return {!Element}
    */
   element() {},
 };