emit timeline_resize in MatrixChat based on ResizeNotifier

as it's used in PersistentElement which could be used at various places

src/components/structures/RoomView.js

@@ -865,10 +865,6 @@ module.exports = React.createClass({
         }
     },
 
-    onSearchResultsResize: function() {
-        dis.dispatch({ action: 'timeline_resize' }, true);
-    },
-
     onSearchResultsFillRequest: function(backwards) {
         if (!backwards) {
             return Promise.resolve(false);
@@ -1803,7 +1799,6 @@ module.exports = React.createClass({
                     <ScrollPanel ref="searchResultsPanel"
                         className="mx_RoomView_messagePanel mx_RoomView_searchResultsPanel"
                         onFillRequest={this.onSearchResultsFillRequest}
-                        onResize={this.onSearchResultsResize}
                     >
                         <li className={scrollheader_classes}></li>
                         { this.getSearchResultTiles() }