Adjust chat tab to the new vue-scroll directive

Due to the changes in the message list it is no longer needed to reset
the height of the chat view. Moreover, the chat view now needs to have a
height of 100% (which was the reset value before) in order to be
properly shown in Chromium.

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>

src/FilesSidebarTabApp.vue

@@ -320,10 +320,6 @@ export default {
 }
 
 .chatView {
-	/* The chat view shares its parent with the call button, so the default
-	 * "height: 100%" needs to be unset. */
-	height: unset;
-
 	overflow: hidden;
 }
 </style>

src/mainChatTab.js

@@ -36,6 +36,7 @@ import { getRequestToken } from '@nextcloud/auth'
 // Directives
 import contenteditableDirective from 'vue-contenteditable-directive'
 import { translate, translatePlural } from '@nextcloud/l10n'
+import vuescroll from 'vue-scroll'
 
 // CSP config for webpack dynamic chunk loading
 // eslint-disable-next-line
@@ -55,6 +56,7 @@ Vue.prototype.OCA = OCA
 
 Vue.use(contenteditableDirective)
 Vue.use(Vuex)
+Vue.use(vuescroll, { debounce: 600 })
 
 const newTab = () => new Vue({
 	store,