[js] Start breaking the http module's dependency on closure

This is the first step in entirely removing the dependency on closure
from the node bindigns.

javascript/node/selenium-webdriver/CHANGES.md

@@ -23,6 +23,9 @@ the selenium-webdriver package README.
     For the export types, the `code` property is now the string code used by
     the W3C spec and _not_ the numeric code used by the Selenium project's
     wire protocol.
+* Rewrote the `http` module to no longer user the Google Closure Library.
+* Changed the `http.Request` and `http.Response` classes to store headers in
+    maps instead of object literals.
 * Updated `ws` dependency to version `1.0.1`.
 
 ### Changes for W3C WebDriver Spec Compliance

javascript/node/selenium-webdriver/error.js

@@ -531,7 +531,7 @@ function checkLegacyResponse(responseObj) {
   // Handle the legacy Selenium error response format.
   if (responseObj
       && typeof responseObj === 'object'
-      && responseObj['status'] === 'number'
+      && typeof responseObj['status'] === 'number'
       && responseObj['status'] !== 0) {
     let status = responseObj['status'];
     let ctor = LEGACY_ERROR_CODE_TO_CLASS.get(status) || WebDriverError;