Upstream service worker `fetch` tests to WPT

third_party/WebKit/LayoutTests/http/tests/serviceworker/resources/fetch-event-network-error-worker.js

-// Test that multiple fetch handlers do not confuse the implementation.
-self.addEventListener('fetch', function(event) {});
-
-self.addEventListener('fetch', function(event) {
-    var testcase = new URL(event.request.url).search;
-    switch (testcase) {
-    case '?reject':
-      event.respondWith(Promise.reject());
-      break;
-    case '?prevent-default':
-      event.preventDefault();
-      break;
-    case '?prevent-default-and-respond-with':
-      event.preventDefault();
-      break;
-    case '?unused-body':
-      event.respondWith(new Response('body'));
-      break;
-    case '?used-body':
-      var res = new Response('body');
-      res.text();
-      event.respondWith(res);
-      break;
-    case '?unused-fetched-body':
-      event.respondWith(fetch('progressive.php').then(function(res){
-          return res;
-        }));
-      break;
-    case '?used-fetched-body':
-      event.respondWith(fetch('progressive.php').then(function(res){
-          res.text();
-          return res;
-        }));
-      break;
-    }
-  });
-
-self.addEventListener('fetch', function(event) {});
-
-self.addEventListener('fetch', function(event) {
-    var testcase = new URL(event.request.url).search;
-    if (testcase == '?prevent-default-and-respond-with')
-      event.respondWith(new Response('responding!'));
-  });
-
-self.addEventListener('fetch', function(event) {});