[DevTools] Remove HelpScreen, turn SettingsScreen into dialog and web component.

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

 /*
  * Copyright 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.
  */
 
 * {
     /* This is required for correct sizing of flex items because we rely
      * on an old version of the flexbox spec.
      * Longer-term we should remove this, see crbug.com/473625 */
@@ skipping 166 matching lines @@
     margin-bottom: -1px;
     padding-bottom: 1px;
     opacity: 1.0 !important;
 }
 
 .editing,
 .editing * {
     color: #222 !important;
     text-decoration: none !important;
 }
+
+.chrome-select {
+    -webkit-appearance: none;
+    -webkit-user-select: none;
+    border: 1px solid rgba(0, 0, 0, 0.25);
+    border-radius: 2px;
+    box-shadow: 0 1px 0 rgba(0, 0, 0, 0.08),
+    inset 0 1px 2px rgba(255, 255, 255, 0.75);
+    color: #444;
+    font: inherit;
+    margin: 0 1px 0 0;
+    outline: none;
+    text-shadow: 0 1px 0 rgb(240, 240, 240);
+    padding-right: 20px;
+    padding-left: 6px;
+    background-image: -webkit-image-set(url(Images/chromeSelect.png) 1x, url(Images/chromeSelect_2x.png) 2x), linear-gradient(#ededed, #ededed 38%, #dedede);
+    background-position: right center;
+    background-repeat: no-repeat;
+    min-height: 24px;
+}
+
+.chrome-select:enabled:hover {
+    background-image: -webkit-image-set(url(Images/chromeSelect.png) 1x, url(Images/chromeSelect_2x.png) 2x), linear-gradient(#f0f0f0, #f0f0f0 38%, #e0e0e0);
+    border-color: rgba(0, 0, 0, 0.3);
+    box-shadow: 0 1px 0 rgba(0, 0, 0, 0.12),
+    inset 0 1px 2px rgba(255, 255, 255, 0.95);
+    color: black;
+}
+
+.chrome-select:enabled:active {
+    background-image: -webkit-image-set(url(Images/chromeSelect.png) 1x, url(Images/chromeSelect_2x.png) 2x), linear-gradient(#e7e7e7, #e7e7e7 38%, #d7d7d7);
+    box-shadow: none;
+    text-shadow: none;
+}
+
+.chrome-select:enabled:focus {
+    /* OVERRIDE */
+    -webkit-transition: border-color 200ms;
+    /* We use border color because it follows the border radius (unlike outline).
+     * This is particularly noticeable on mac. */
+    border-color: rgb(77, 144, 254);
+    outline: none;
+}
+
+body.inactive select.chrome-select,
+.chrome-select:disabled {
+    background-image: -webkit-image-set(url(Images/chromeDisabledSelect.png) 1x, url(Images/chromeDisabledSelect_2x.png) 2x), linear-gradient(#f1f1f1, #f1f1f1 38%, #e6e6e6);
+    border-color: rgba(80, 80, 80, 0.2);
+    box-shadow: 0 1px 0 rgba(80, 80, 80, 0.08),
+    inset 0 1px 2px rgba(255, 255, 255, 0.75);
+    color: #aaa;
+}