Auto merge of #12636 - jdm:headerstests, r=pcwalton

Enable Headers API tests.

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] There are tests for these changes

This will be useful for #12634.

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/12636)
<!-- Reviewable:end -->

tests/wpt/include.ini

@@ -17,6 +17,12 @@ skip: true
   skip: false
 [eventsource]
   skip: false
+[fetch]
+  skip: true
+  [api]
+    skip: true
+    [headers]
+      skip: false
 [FileAPI]
   skip: false
 [hr-time]

tests/wpt/metadata/fetch/api/headers/headers-basic.html.ini

@@ -0,0 +1,50 @@
+[headers-basic.html]
+  type: testharness
+  [Create headers from no parameter]
+    expected: FAIL
+
+  [Create headers from undefined parameter]
+    expected: FAIL
+
+  [Create headers from empty object]
+    expected: FAIL
+
+  [Create headers with sequence]
+    expected: FAIL
+
+  [Create headers with OpenEndedDictionary]
+    expected: FAIL
+
+  [Create headers whith existing headers]
+    expected: FAIL
+
+  [Check append method]
+    expected: FAIL
+
+  [Check set method]
+    expected: FAIL
+
+  [Check has method]
+    expected: FAIL
+
+  [Check delete method]
+    expected: FAIL
+
+  [Check get method]
+    expected: FAIL
+
+  [Check keys method]
+    expected: FAIL
+
+  [Check values method]
+    expected: FAIL
+
+  [Check entries method]
+    expected: FAIL
+
+  [Check Symbol.iterator method]
+    expected: FAIL
+
+  [Check forEach method]
+    expected: FAIL
+

tests/wpt/metadata/fetch/api/headers/headers-casing.html.ini

@@ -0,0 +1,14 @@
+[headers-casing.html]
+  type: testharness
+  [Create headers, names use characters with different case]
+    expected: FAIL
+
+  [Check append method, names use characters with different case]
+    expected: FAIL
+
+  [Check set method, names use characters with different case]
+    expected: FAIL
+
+  [Check delete method, names use characters with different case]
+    expected: FAIL
+

tests/wpt/metadata/fetch/api/headers/headers-combine.html.ini

@@ -0,0 +1,14 @@
+[headers-combine.html]
+  type: testharness
+  [Create headers using same name for different values]
+    expected: FAIL
+
+  [Check delete and has methods when using same name for different values]
+    expected: FAIL
+
+  [Check set methods when called with already used name]
+    expected: FAIL
+
+  [Check append methods when called with already used name]
+    expected: FAIL
+

tests/wpt/metadata/fetch/api/headers/headers-errors.html.ini

@@ -0,0 +1,44 @@
+[headers-errors.html]
+  type: testharness
+  [Check headers get with an invalid name invalidĀ]
+    expected: FAIL
+
+  [Check headers get with an invalid name [object Object\]]
+    expected: FAIL
+
+  [Check headers delete with an invalid name invalidĀ]
+    expected: FAIL
+
+  [Check headers delete with an invalid name [object Object\]]
+    expected: FAIL
+
+  [Check headers has with an invalid name invalidĀ]
+    expected: FAIL
+
+  [Check headers has with an invalid name [object Object\]]
+    expected: FAIL
+
+  [Check headers set with an invalid name invalidĀ]
+    expected: FAIL
+
+  [Check headers set with an invalid name [object Object\]]
+    expected: FAIL
+
+  [Check headers set with an invalid value invalidĀ]
+    expected: FAIL
+
+  [Check headers append with an invalid name invalidĀ]
+    expected: FAIL
+
+  [Check headers append with an invalid name [object Object\]]
+    expected: FAIL
+
+  [Check headers append with an invalid value invalidĀ]
+    expected: FAIL
+
+  [Headers forEach throws if argument is not callable]
+    expected: FAIL
+
+  [Headers forEach loop should stop if callback is throwing exception]
+    expected: FAIL
+

tests/wpt/metadata/fetch/api/headers/headers-idl.html.ini

@@ -0,0 +1,3 @@
+[headers-idl.html]
+  type: testharness
+  expected: TIMEOUT

tests/wpt/metadata/fetch/api/headers/headers-normalize.html.ini

@@ -0,0 +1,11 @@
+[headers-normalize.html]
+  type: testharness
+  [Create headers with not normalized values]
+    expected: FAIL
+
+  [Check append method whith not normalized values]
+    expected: FAIL
+
+  [Check set method whith not normalized values]
+    expected: FAIL
+

tests/wpt/metadata/fetch/api/headers/headers-structure.html.ini

@@ -0,0 +1,3 @@
+[headers-structure.html]
+  type: testharness
+  expected: TIMEOUT