Bug 1546041 - Throw TypeError if mode is Navigate r=baku

According to spec, we should throw TypeError if the mode is Navigate.

Differential Revision: https://phabricator.services.mozilla.com/D31245

--HG--
extra : moz-landing-system : lando

dom/fetch/Request.cpp

@@ -322,9 +322,11 @@ already_AddRefed<Request> Request::Constructor(const GlobalObject& aGlobal,
                                        ? aInit.mCredentials.Value()
                                        : fallbackCredentials;
 
-  if (mode == RequestMode::Navigate ||
-      (aInit.IsAnyMemberPresent() &&
-       request->Mode() == RequestMode::Navigate)) {
+  if (mode == RequestMode::Navigate) {
+    aRv.ThrowTypeError<MSG_INVALID_REQUEST_MODE>(NS_LITERAL_STRING("navigate"));
+    return nullptr;
+  }
+  if (aInit.IsAnyMemberPresent() && request->Mode() == RequestMode::Navigate) {
     mode = RequestMode::Same_origin;
   }
 

testing/web-platform/meta/fetch/api/request/request-error.html.ini

@@ -2,9 +2,6 @@
   [RequestInit's window is not null]
     expected: FAIL
 
-  [RequestInit's mode is navigate]
-    expected: FAIL
-
   [RequestInit's mode is no-cors and integrity is not empty]
     expected: FAIL