Introduce Response.redirect attribute and add LayoutTest.

third_party/WebKit/LayoutTests/http/tests/fetch/script-tests/response.js

 if (self.importScripts) {
   importScripts('../resources/fetch-test-helpers.js');
   importScripts('/streams/resources/rs-utils.js');
 }
 
 function decode(chunks) {
   var decoder = new TextDecoder();
   var result = '';
   for (var chunk of chunks) {
     result += decoder.decode(chunk, {stream: true});
   }
   result += decoder.decode(new Uint8Array(0));
   return result;
 }
 
 test(function() {
     var response = new Response();
     assert_equals(response.type, 'default',
                   'Default Response.type should be \'default\'');
     assert_equals(response.url, '', 'Response.url should be the empty string');
+    assert_false(response.redirected, 'Response.redirected should be false.');
     assert_equals(response.status, 200,
                   'Default Response.status should be 200');
     assert_true(response.ok, 'Default Response.ok must be true');
     assert_equals(response.statusText, 'OK',
                   'Default Response.statusText should be \'OK\'');
     assert_equals(size(response.headers), 0,
                   'Default Response should not have any header.');
     if (self.internals) {
       var urlList = self.internals.getInternalResponseURLList(response);
       assert_equals(urlList.length, 0,
@@ skipping 428 matching lines @@
 test(function() {
     ['http://ex\x0aample.com',
      'http://ex\x0dample.com'].forEach(function(url) {
         assert_equals(Response.redirect(url).headers.get('Location'),
                       'http://example.com/',
                       'Location header value must not contain CR or LF');
       });
   }, 'Response.redirect() with URLs with CR or LF');
 
 done();