DevTools: fix console to tail messages on devtools with zoomfactor != 1

Source/devtools/front_end/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 157 matching lines @@
         this.style.removeProperty("left");
 
     if (typeof y === "number")
         this.style.setProperty("top", (shift.y + y) + "px");
     else
         this.style.removeProperty("top");
 }
 
 Element.prototype.isScrolledToBottom = function()
 {
-    // This code works only for 0-width border
-    return this.scrollTop + this.clientHeight === this.scrollHeight;
+    // This code works only for 0-width border.
+    // Both clientHeight and scrollHeight are rounded to integer values, so we tolerate
+    // one pixel error.
+    return Math.abs(this.scrollTop + this.clientHeight - this.scrollHeight) <= 1;
 }
 
 /**
  * @param {!Node} fromNode
  * @param {!Node} toNode
  */
 function removeSubsequentNodes(fromNode, toNode)
 {
     for (var node = fromNode; node && node !== toNode; ) {
         var nodeToRemove = node;
@@ skipping 372 matching lines @@
  */
 function isEnterKey(event) {
     // Check if in IME.
     return event.keyCode !== 229 && event.keyIdentifier === "Enter";
 }
 
 function consumeEvent(e)
 {
     e.consume();
 }