Fix JSHint errors in heartbeat.js.

props dziudek.
fixes #25986.

Built from https://develop.svn.wordpress.org/trunk@26197


git-svn-id: http://core.svn.wordpress.org/trunk@26105 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/js/heartbeat.js

@@ -224,7 +224,7 @@
 							trigger = true;
 							break;
 						}
-						// Pass through other error statuses
+						/* falls through */
 					case 'parsererror':
 					case 'empty':
 					case 'unknown':
@@ -594,7 +594,6 @@
 						// Allow long polling, (experimental)
 						settings.mainInterval = 0;
 						return 0;
-						break;
 					default:
 						interval = settings.originalInterval;
 				}