Reuse empty _query objects.

Author: STRML

Diff for: lib/matchRoutes.js

@@ -117,13 +117,15 @@ function Match(path, route, match, query) {
     this.path;
 }
 
+const EMPTY_OBJECT = {}; // Maintains reference equality, useful for SCU
+Object.freeze && Object.freeze(EMPTY_OBJECT);
 Match.prototype.getProps = function() {
   if (!this.route) {
     throw new Error("React-router-component: No route matched! Did you define a NotFound route?");
   }
   var props = assign({}, this.route.props, this.match);
   // Querystring is assigned as _query.
-  props._query = this.query || {};
+  props._query = this.query || EMPTY_OBJECT;
 
   // Delete props that shouldn't be passed to the handler.
   delete props.pattern;