Fix sorting of search result highlights

Make sure that we *actually* give preference to longer search result
highlights; it turns out that the code that looked like it was doing so has
never worked.

src/components/structures/RoomView.js

@@ -553,7 +553,8 @@ module.exports = React.createClass({
 
             // For overlapping highlights,
             // favour longer (more specific) terms first
-            highlights = highlights.sort(function(a, b) { b.length - a.length });
+            highlights = highlights.sort(function(a, b) {
+                return b.length - a.length });
 
             self.setState({
                 searchHighlights: highlights,