[3/3 blink] Support redirect option of Request and "opaqueredirect" response type.

LayoutTests/http/tests/serviceworker/resources/fetch-rewrite-worker.js

 function get_query_params(url) {
   var search = (new URL(url)).search;
   if (!search) {
     return {};
   }
   var ret = {};
   var params = search.substring(1).split('&');
   params.forEach(function(param) {
       var element = param.split('=');
       ret[decodeURIComponent(element[0])] = decodeURIComponent(element[1]);
     });
   return ret;
 }
 
 function get_request_init(params) {
   var init = {};
   if (params['method']) {
     init['method'] = params['method'];
   }
   if (params['mode']) {
     init['mode'] = params['mode'];
   }
   if (params['credentials']) {
     init['credentials'] = params['credentials'];
   }
+  if (params['redirect-mode']) {
+    init['redirect'] = params['redirect-mode'];
+  }
   return init;
 }
 
 self.addEventListener('fetch', function(event) {
     var params = get_query_params(event.request.url);
     var init = get_request_init(params);
     var url = params['url'];
     if (params['ignore']) {
       return;
     }
@@ skipping 22 matching lines @@
       return;
     }
     event.respondWith(new Promise(function(resolve, reject) {
         var request = event.request;
         if (url) {
           request = new Request(url, init);
         }
         fetch(request).then(resolve, reject);
       }));
   });