use main element for room/group view

src/components/structures/GroupView.js

@@ -1292,7 +1292,7 @@ export default React.createClass({
             };
 
             return (
-                <div className="mx_GroupView">
+                <main className="mx_GroupView">
                     <div className={classnames(headerClasses)}>
                         <div className="mx_GroupView_header_leftCol">
                             <div className="mx_GroupView_header_avatar">
@@ -1318,7 +1318,7 @@ export default React.createClass({
                             { this._getGroupSection() }
                         </GeminiScrollbarWrapper>
                     </MainSplit>
-                </div>
+                </main>
             );
         } else if (this.state.error) {
             if (this.state.error.httpStatus === 404) {

src/components/structures/RoomView.js

@@ -1820,7 +1820,7 @@ module.exports = React.createClass({
         const rightPanel = this.state.room ? <RightPanel roomId={this.state.room.roomId} /> : undefined;
 
         return (
-            <div className={"mx_RoomView" + (inCall ? " mx_RoomView_inCall" : "")} ref="roomView">
+            <main className={"mx_RoomView" + (inCall ? " mx_RoomView_inCall" : "")} ref="roomView">
                 <RoomHeader ref="header" room={this.state.room} searchInfo={searchInfo}
                     oobData={this.props.oobData}
                     editing={this.state.editingRoomSettings}
@@ -1850,7 +1850,7 @@ module.exports = React.createClass({
                         { messageComposer }
                     </div>
                 </MainSplit>
-            </div>
+            </main>
         );
     },
 });