Introduce Response.redirect attribute and add LayoutTest.

third_party/WebKit/LayoutTests/http/tests/fetch/script-tests/thorough/redirect-loop.js

 if (self.importScripts) {
   importScripts('/fetch/resources/fetch-test-helpers.js');
   importScripts('/fetch/resources/thorough-util.js');
 }
 
 function createExpectedURLList(prefix, count, last) {
   var array = [];
   for (var i = count; i > 0; --i)
     array.push(prefix + i);
   array.push(last);
   return array;
 }
 
 var TEST_TARGETS = [
   // Redirect loop: same origin -> same origin
   [REDIRECT_LOOP_URL + encodeURIComponent(BASE_URL) + '&Count=20&mode=cors' +
    '&credentials=same-origin',
    [fetchResolved, hasContentLength, hasBody, typeBasic,
+    responseRedirected,
     checkURLList.bind(
         self,
         createExpectedURLList(
             REDIRECT_LOOP_URL + encodeURIComponent(BASE_URL) + '&Count=',
             19, BASE_URL))],
    [methodIsGET, authCheck1]],
   [REDIRECT_LOOP_URL + encodeURIComponent(BASE_URL) + '&Count=21&mode=cors' +
    '&credentials=same-origin',
    [fetchRejected]],
 
   // Redirect loop: same origin -> other origin
   [REDIRECT_LOOP_URL + encodeURIComponent(OTHER_BASE_URL + '&ACAOrigin=*') +
    '&Count=20&mode=cors&credentials=same-origin&method=GET',
    [fetchResolved, noContentLength, noServerHeader, hasBody, typeCors,
+    responseRedirected,
     checkURLList.bind(
         self,
         createExpectedURLList(
             REDIRECT_LOOP_URL +
             encodeURIComponent(OTHER_BASE_URL + '&ACAOrigin=') + '%2A&Count=',
             19,
             OTHER_BASE_URL + '&ACAOrigin=*'))],
    [methodIsGET, authCheckNone]],
   // FIXME: due to the current implementation of Chromium,
   // Count=21 is resolved, Count=22 is rejected.
   // https://crbug.com/353768
   [REDIRECT_LOOP_URL + encodeURIComponent(OTHER_BASE_URL + '&ACAOrigin=*') +
    '&Count=22&mode=cors&credentials=same-origin&method=GET',
    [fetchRejected]],
 
   // Redirect loop: other origin -> same origin
   [OTHER_REDIRECT_LOOP_URL + encodeURIComponent(BASE_URL + 'ACAOrigin=*') +
    '&Count=20&mode=cors&credentials=same-origin&method=GET&ACAOrigin=*',
    [fetchResolved, noContentLength, noServerHeader, hasBody, typeCors,
+    responseRedirected,
     checkURLList.bind(
         self,
         createExpectedURLList(
             OTHER_REDIRECT_LOOP_URL +
             encodeURIComponent(BASE_URL + 'ACAOrigin=') +
             '%2A&ACAOrigin=*&Count=',
             19,
             BASE_URL + 'ACAOrigin=*'))],
    [methodIsGET, authCheckNone]],
   [OTHER_REDIRECT_LOOP_URL + encodeURIComponent(BASE_URL + 'ACAOrigin=*') +
    '&Count=21&mode=cors&credentials=same-origin&method=GET&ACAOrigin=*',
    [fetchRejected]],
 
   // Redirect loop: other origin -> other origin
   [OTHER_REDIRECT_LOOP_URL +
    encodeURIComponent(OTHER_BASE_URL + 'ACAOrigin=*') +
    '&Count=20&mode=cors&credentials=same-origin&method=GET&ACAOrigin=*',
    [fetchResolved, noContentLength, noServerHeader, hasBody, typeCors,
+    responseRedirected,
     checkURLList.bind(
         self,
         createExpectedURLList(
             OTHER_REDIRECT_LOOP_URL +
             encodeURIComponent(OTHER_BASE_URL + 'ACAOrigin=') +
             '%2A&ACAOrigin=*&Count=',
             19,
             OTHER_BASE_URL + 'ACAOrigin=*'))],
    [methodIsGET, authCheckNone]],
   [OTHER_REDIRECT_LOOP_URL +
    encodeURIComponent(OTHER_BASE_URL + 'ACAOrigin=*') +
    '&Count=21&mode=cors&credentials=same-origin&method=GET&ACAOrigin=*',
    [fetchRejected]],
 ];
 
 if (self.importScripts) {
   executeTests(TEST_TARGETS);
   done();
 }