[DevTools] Add groups to device select.

Source/devtools/front_end/responsiveDesignView.css

 /*
  * Copyright 2014 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.
  */
 
 .responsive-design {
     overflow: hidden;
     position: relative;
 }
@@ skipping 97 matching lines @@
     background-color: rgb(43, 43, 43);
     margin: 0 3px;
 }
 
 .responsive-design-suite > div:not(.responsive-design-suite-separator) {
     flex: none;
     display: flex;
     flex-direction: row;
     align-items: center;
     justify-content: space-between;
-    height: 22px;
+    height: 23px;
     overflow: hidden;
 }
 
 /* Toolbar controls */
 
 .responsive-design-toolbar fieldset,
 .responsive-design-toolbar p {
     margin: 0;
     border: 0;
     padding: 0;
     display: inline-block;
 }
 
 .responsive-design-toolbar .field-error-message {
     display: none;
 }
 
 .responsive-design-toolbar label {
     margin-right: 5px;
     cursor: default !important;
 }
 
 .responsive-design-toolbar input[type='text'] {
     text-align: left;
     background-color: transparent;
     border: none;
-    margin: 0;
-    margin-bottom: 4px;
+    margin: 0 1px 1px 0;
     padding: 3px 2px;
 }
 
 .responsive-design-toolbar input[type='text'].numeric {
     text-align: center;
 }
 
 .responsive-design-toolbar input:focus::-webkit-input-placeholder {
     color: transparent !important;
 }
@@ skipping 128 matching lines @@
     opacity: 0.8;
 }
 
 /* Device section */
 
 .responsive-design-section-device .responsive-design-section-separator {
     background: linear-gradient(to bottom, rgb(255, 186, 68), rgb(255, 119, 0));
 }
 
 .responsive-design-section-device select {
-    width: 220px;
+    width: 180px;
 }
 
 .responsive-design-section-device input[type='text'],
 .responsive-design-section-device input[type='text']::-webkit-input-placeholder,
 .responsive-design-section-device select {
     color: rgb(255, 156, 0);
 }
 
 .responsive-design-section-device input[type='checkbox']:checked:after {
     background: rgb(255, 156, 0);
@@ skipping 31 matching lines @@
     padding: 2px 4px;
     white-space: nowrap;
     display: flex;
     align-items: center;
     border-bottom: 1px solid rgb(171, 171, 171);
 }
 
 .responsive-design-warning > span {
     flex: auto;
     padding-left: 3px;
+    overflow: hidden;
 }
+
+.responsive-design-warning > div {
+    flex: none;
+}