WPT: Tentative test HTTP cache vs credentials.

Add a test. Check whether the HTTP cache discriminate the credentialled
requests from the anonymous ones.

The expectations used are the ones from the specification. That's also
Firefox's behavior.
Chrome fails the test. Safari fail similarly + do not support
SharedWorker.
At some point, we would like to make Chrome to converge with the spec,
or update with the specification.

whatwg/fetch issue:
whatwg/fetch#307
whatwg/fetch#1253

Design doc:
https://docs.google.com/document/d/1lvbiy4n-GM5I56Ncw304sgvY5Td32R6KHitjRXvkZ6U/edit#

Test results:
https://github.com/web-platform-tests/wpt/pull/29867/checks?check_run_id=3279839968
┌────────────────────────────────────────────┬───────┬───────┬────────┐
│Test                                        │ Chrome│ Safari│ Firefox│
├────────────────────────────────────────────┼───────┼───────┼────────┤
│credentials.tentative.any.html              │ 1/3   │ 1/3   │ 3/3    │
├────────────────────────────────────────────┼───────┼───────┼────────┤
│credentials.tentative.any.serviceworker.html│ 1/3   │ 1/3   │ 3/3    │
├────────────────────────────────────────────┼───────┼───────┼────────┤
│credentials.tentative.any.sharedworker.html │ 1/3   │ 0/3   │ 3/3    │
├────────────────────────────────────────────┼───────┼───────┼────────┤
│credentials.tentative.any.worker.html       │ 1/3   │ 1/3   │ 3/3    │
└────────────────────────────────────────────┴───────┴───────┴────────┘

Bug:1221529
Change-Id: I0537108f473f37f42eef7b4fa1079cd88d987b62

fetch/http-cache/credentials.tentative.any.js

@@ -0,0 +1,62 @@
+// META: global=window,worker
+// META: title=HTTP Cache - Content
+// META: timeout=long
+// META: script=/common/utils.js
+// META: script=http-cache.js
+
+// This is a tentative test.
+// Firefox behavior is used as expectations.
+//
+// whatwg/fetch issue:
+// https://github.com/whatwg/fetch/issues/1253
+//
+// Chrome design doc:
+// https://docs.google.com/document/d/1lvbiy4n-GM5I56Ncw304sgvY5Td32R6KHitjRXvkZ6U/edit#
+
+const request_cacheable = {
+  request_headers: [],
+  response_headers: [
+    ['Cache-Control', 'max-age=3600'],
+  ],
+  // TODO(arthursonzogni): The behavior is tested only for same-origin requests.
+  // It must behave similarly for cross-site and cross-origin requests. The
+  // problems is the http-cache.js infrastructure returns the
+  // "Server-Request-Count" as HTTP response headers, which aren't readable for
+  // CORS requests.
+  base_url: location.href.replace(/\/[^\/]*$/, '/'),
+};
+
+const request_credentialled = { ...request_cacheable, credentials: 'include', };
+const request_anonymous     = { ...request_cacheable, credentials: 'omit', };
+
+const responseIndex = count => {
+  return {
+    expected_response_headers: [
+      ['Server-Request-Count', count.toString()],
+    ],
+  }
+};
+
+var tests = [
+  {
+    name: 'same-origin: 2xAnonymous, 2xCredentialled, 1xAnonymous',
+    requests: [
+      { ...request_anonymous     , ...responseIndex(1)} ,
+      { ...request_anonymous     , ...responseIndex(1)} ,
+      { ...request_credentialled , ...responseIndex(2)} ,
+      { ...request_credentialled , ...responseIndex(2)} ,
+      { ...request_anonymous     , ...responseIndex(1)} ,
+    ]
+  },
+  {
+    name: 'same-origin: 2xCredentialled, 2xAnonymous, 1xCredentialled',
+    requests: [
+      { ...request_credentialled , ...responseIndex(1)} ,
+      { ...request_credentialled , ...responseIndex(1)} ,
+      { ...request_anonymous     , ...responseIndex(2)} ,
+      { ...request_anonymous     , ...responseIndex(2)} ,
+      { ...request_credentialled , ...responseIndex(1)} ,
+    ]
+  },
+];
+run_tests(tests);