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 Firefox's behavior.
Chrome fail the test. Later, I would like to make Chrome to converge
toward Firefox and run a performance experiment.

whatwg/fetch issue:
whatwg/fetch#1253

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

See:
https://github.com/web-platform-tests/wpt/pull/29867/checks?check_run_id=3222766321

Once:
#29612 (comment)
resolved, I am expecting:
┌────────────────────────────────────────────┬───────┬───────┬────────┐
│Test                                        │ Chrome│ Safari│ Firefox│
├────────────────────────────────────────────┼───────┼───────┼────────┤
│credentials.tentative.any.html              │ FAIL  │ Fail  │ PASS   │
├────────────────────────────────────────────┼───────┼───────┼────────┤
│credentials.tentative.any.serviceworker.html│ FAIL  │ FAIL  │ PASS   │
├────────────────────────────────────────────┼───────┼───────┼────────┤
│credentials.tentative.any.sharedworker.html │ FAIL  │ FAIL  │ PASS   │
├────────────────────────────────────────────┼───────┼───────┼────────┤
│credentials.tentative.any.worker.html       │ FAIL  │ FAIL  │ PASS   │
└────────────────────────────────────────────┴───────┴───────┴────────┘

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);