DevTools: Always have some content in a TextPrompt

third_party/WebKit/Source/devtools/front_end/ui/textPrompt.css

 /*
  * Copyright (c) 2015 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 .text-prompt-root {
     display: flex;
     align-items: center;
 }
@@ skipping 27 matching lines @@
     color: rgb(128, 128, 128) !important;
     -webkit-user-select: none;
     -webkit-user-modify: read-only;
 }
 
 ::content .text-prompt[data-placeholder]:empty::before {
     content: attr(data-placeholder);
     color: rgb(128, 128, 128);
 }
 
+::content .text-prompt:empty::after {
+    content: '\00A0';
+    width: 0;
+    display: block;
+}
+
 .text-prompt-editing ::content br {
     display: none;
 }