feat(chat): Improve responsiveness.

* Fix toolbox buttons not displaying properly when chat is open.
* Open chat in fullscreen dialog past custom thresholds when mobile/desktop toolbox would become unusable due to chat
* Remove mobile chat check when displaying toolbox

react/features/chat/components/web/ChatDialog.js

@@ -0,0 +1,37 @@
+// @flow
+
+import React from 'react';
+
+import { Dialog } from '../../../base/dialog';
+
+import Header from './ChatDialogHeader';
+
+type Props = {
+
+    /**
+     * Children of the component.
+     */
+    children: React$Node
+}
+
+/**
+ * Component that renders the content of the chat in a modal.
+ *
+ * @returns {React$Element<any>}
+ */
+function ChatDialog({ children }: Props) {
+    return (
+        <Dialog
+            customHeader = { Header }
+            disableEnter = { true }
+            hideCancelButton = { true }
+            submitDisabled = { true }
+            titleKey = 'chat.title'>
+            <div className = 'chat-dialog'>
+                {children}
+            </div>
+        </Dialog>
+    );
+}
+
+export default ChatDialog;