DevTools: speed up network scrolling and layout.

Source/devtools/front_end/inspector.css

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2009 Anthony Ricaud <rik@webkit.org>
  *
  * 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 808 matching lines @@
     overflow: hidden;
 }
 
 #console-messages {
     flex: 1 1;
     padding: 2px 0;
     overflow-y: auto;
     word-wrap: break-word;
     -webkit-user-select: text;
     border-top: 1px solid rgb(230, 230, 230);
+    -webkit-transform: translateZ(0);
 }
 
 #console-prompt {
     clear: right;
     position: relative;
     padding: 1px 22px 1px 0;
     margin-left: 24px;
     min-height: 16px;
     white-space: pre-wrap;
     -webkit-user-modify: read-write-plaintext-only;
@@ skipping 2006 matching lines @@
 }
 
 .root-view > .split-view > .split-view-sidebar {
     position: relative;
 }
 
 select.drop-down-menu {
     border: none;
     -webkit-appearance: none;
 }