DevTools: Fix text going out when adding a new Watch Expression.

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 1710 matching lines @@
     padding-left: 15px;
 }
 
 .properties-tree.watch-expressions > li.hovered {
     padding-right: 14px;
 }
 
 .watch-expressions > li.editing-sub-part .text-prompt {
     display: block;
     width: 100%;
+    overflow: hidden;
 }
 
 .watch-expressions > li.editing-sub-part .value,
 .watch-expressions > li.editing-sub-part .separator  {
     display: none;
 }
 
 .section .properties li.editing-sub-part {
     padding: 3px 6px 8px 18px;
     margin: -3px -6px -8px -6px;
@@ skipping 1142 matching lines @@
 }
 
 .root-view > .split-view > .split-view-sidebar {
     position: relative;
 }
 
 select.drop-down-menu {
     border: none;
     -webkit-appearance: none;
 }