Removed import of url module in browser build due to significant size overhead; (#4594)

Removed pointless `Malformed URL` checking in  client build;

lib/adapters/http.js

@@ -17,6 +17,8 @@ var CanceledError = require('../cancel/CanceledError');
 
 var isHttps = /https:?/;
 
+var supportedProtocols = [ 'http:', 'https:', 'file:' ];
+
 /**
  *
  * @param {http.ClientRequestArgs} options
@@ -129,9 +131,9 @@ module.exports = function httpAdapter(config) {
     // Parse url
     var fullPath = buildFullPath(config.baseURL, config.url);
     var parsed = url.parse(fullPath);
-    var protocol = utils.getProtocol(parsed.protocol);
+    var protocol = parsed.protocol || supportedProtocols[0];
 
-    if (!utils.supportedProtocols.includes(protocol)) {
+    if (supportedProtocols.indexOf(protocol) === -1) {
       return reject(new AxiosError(
         'Unsupported protocol ' + protocol,
         AxiosError.ERR_BAD_REQUEST,