Add aria-live to network status area, left pane, and timeline

background.html

@@ -53,7 +53,7 @@
 
   <script type='text/x-tmpl-mustache' id='two-column'>
     <div class='gutter'>
-      <div class='network-status-container'></div>
+      <div class='network-status-container' aria-live='assertive'></div>
       <div class='left-pane-placeholder'></div>
     </div>
     <div class='conversation-stack'>
@@ -93,7 +93,7 @@
   <script type='text/x-tmpl-mustache' id='conversation'>
     <div class='conversation-header'></div>
     <div class='main panel'>
-      <div class='timeline-placeholder'></div>
+      <div class='timeline-placeholder' aria-live='polite'></div>
       <div class='bottom-bar' id='footer'>
         <div class='compose'>
           <form class='send clearfix file-input'>

ts/components/LeftPane.tsx

@@ -171,7 +171,7 @@ export class LeftPane extends React.Component<PropsType> {
     //   it re-renders when our conversation data changes. Otherwise it would just render
     //   on startup and scroll.
     const list = (
-      <div className="module-left-pane__list" key={listKey}>
+      <div className="module-left-pane__list" key={listKey} aria-live="polite">
         <AutoSizer>
           {({ height, width }) => (
             <List

ts/components/SearchResults.tsx

@@ -306,7 +306,7 @@ export class SearchResults extends React.Component<PropsType> {
     }
 
     return (
-      <div className="module-search-results">
+      <div className="module-search-results" aria-live="polite">
         <AutoSizer>
           {({ height, width }) => {
             this.mostRecentWidth = width;