lib,test: update in preparation for linter update

ESLint 2.9.0 fixes some bugs that resulted in minor issues not being
caught by ESLint 2.7.0. Update instances of our code that will be
flagged when we upgrade to ESLint 2.9.0.

PR-URL: #6498
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>

Author: Trott

lib/buffer.js

@@ -263,6 +263,7 @@ function byteLength(string, encoding) {
       case 'ascii':
       case 'binary':
       // Deprecated
+      // eslint-disable-next-line no-fallthrough
       case 'raw':
       case 'raws':
         return len;

lib/readline.js

@@ -977,6 +977,7 @@ exports.emitKeypressEvents = emitKeypressEvents;
 */
 
 // Regexes used for ansi escape code splitting
+// eslint-disable-next-line no-control-regex
 const metaKeyCodeReAnywhere = /(?:\x1b)([a-zA-Z0-9])/;
 const functionKeyCodeReAnywhere = new RegExp('(?:\x1b+)(O|N|\\[|\\[\\[)(?:' + [
   '(\\d+)(?:;(\\d+))?([~^$])',

test/parallel/test-http-destroyed-socket-write2.js

@@ -29,12 +29,17 @@ server.listen(common.PORT, function() {
     switch (er.code) {
       // This is the expected case
       case 'ECONNRESET':
-      // On windows this sometimes manifests as ECONNABORTED
+        break;
+
+      // On Windows, this sometimes manifests as ECONNABORTED
       case 'ECONNABORTED':
+        break;
+
       // This test is timing sensitive so an EPIPE is not out of the question.
       // It should be infrequent, given the 50 ms timeout, but not impossible.
       case 'EPIPE':
         break;
+
       default:
         assert.strictEqual(er.code,
           'ECONNRESET',