Bug 1571567 - Fix no-fallthrough errors in /js. r=jorendorff

Differential Revision: https://phabricator.services.mozilla.com/D40875

--HG--
extra : moz-landing-system : lando

js/src/builtin/TypedObject.js

@@ -497,6 +497,7 @@ function TypedObjectArrayTypeBuild(a, b, c) {
       ThrowTypeError(JSMSG_TYPEDOBJECT_BAD_ARGS);
     else
       ThrowTypeError(JSMSG_TYPEDOBJECT_BAD_ARGS);
+      break;
   default:
     ThrowTypeError(JSMSG_TYPEDOBJECT_BAD_ARGS);
   }