Bug 1872151 - Update top-level comment in MapAndSet.h. r=spidermonkey-reviewers,arai DONTBUILD

Differential Revision: https://phabricator.services.mozilla.com/D197339

js/public/MapAndSet.h

@@ -5,7 +5,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 /*
- * Weak Maps.
+ * Maps and Sets.
  */
 
 #ifndef js_MapAndSet_h