Revert "Cancel quick-search on Escape, clearing it and returning focus to composer."

This reverts commit 52a119244b.

src/components/structures/SearchBox.js

@@ -100,10 +100,6 @@ module.exports = React.createClass({
         }
 
         switch (ev.keyCode) {
-            case KeyCode.ESCAPE:
-                this._clearSearch();
-                dis.dispatch({action: 'focus_composer'});
-                break;
             case KeyCode.KEY_K:
                 if (ctrlCmdOnly) {
                     if (this.refs.search) {