build: use connect web server instead of SimpleHTTPServer

Several flakes on CI have been tied to long running SimpleHTTPServer that was
put in place temporarily after the package splitup.

tools/build/jsserve.js

@@ -1,42 +0,0 @@
-var onHeaders = require('on-headers');
-var proxy = require('proxy-middleware');
-var cors = require('cors');
-var url = require('url');
-
-module.exports = function(gulp, plugins, config) {
-  return function() {
-    plugins.connect.server({
-      root: [__dirname + '/../../' + config.path],
-      port: config.port,
-      livereload: false,
-      open: false,
-      middleware: function(connect, opt) {
-        config.proxies = config.proxies || [];
-        var middlewares =
-            config.proxies.map(function(entry) { return makeProxy(entry.route, entry.url); });
-        middlewares.push(connect.favicon());
-        middlewares.push(cors());
-        // pub serve can't give the right content-type header for jsonp requests
-        // so we must turn off Chromium strict MIME type checking
-        // see https://github.com/angular/angular/issues/3030#issuecomment-123453168
-        middlewares.unshift(stripHeader('x-content-type-options'));
-        return middlewares;
-      }
-    });
-  };
-};
-
-function makeProxy(route, urlParam) {
-  var options = url.parse(urlParam);
-  options.route = route;
-  return proxy(options);
-}
-
-function stripHeader(toStrip) {
-  return function(req, res, next) {
-    onHeaders(res, function onHeaders() {
-      res.removeHeader(toStrip);
-    });
-    next();
-  };
-}