Support multi-line braille in the virtual braille display.

chrome/browser/resources/chromeos/chromevox/cvox2/background/panel.css

 /* Copyright 2016 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. */
 
 body {
   border: 0;
   height: 35px;
   margin: 0;
   overflow: hidden;
   padding: 0;
@@ skipping 83 matching lines @@
   overflow: hidden;
 }
 
 .usertext {
   font-style: italic;
   font-weight: 700;
 }
 
 #braille-container {
   height: 35px;
+  overflow: hidden;
   position: relative;
   top: -35px;
 }
 
+#braille-container * {
+  border-spacing: 0;
+  color: #fff;
+}
+
+#braille-table-holder-outer {
+  display: flex;
+  height: 100%;
+  overflow: scroll;
+  padding-bottom: 17px;
+  padding-right: 17px;
+  width: 100%;
+}
+
+.braille-table-holder {
+  flex-grow: 1;
+}
+
 #braille-text {
   font-family: 'Droid Sans Mono', Courier, monospace;
   font-size: 12pt;
   height: 17px;
   letter-spacing: 3.13px;
   line-height: 17px;
   white-space: pre;
 }
 
 #braille-cells {
@@ skipping 174 matching lines @@
 #tutorial_footer button {
   background-color: #fff;
   border: 1px solid #000;
   font-family: 'Roboto', sans-serif;
   font-size: 20pt;
   height: 2em;
   margin: 0 24px;
   width: 8em;
 }
 
-table#braille-table {
-  border: none;
-  border-spacing: 0;
+.highlighted-cell {
+  border: 1px solid white;
 }
 
-table#braille-table * {
-  color: #fff;
+.unhighlighted-cell {
+  border: 1px solid black;
 }
-
-table#braille-table tr:first-child {
-  font-size: 85%;
-}