[Fetch] Check / Set .bodyUsed in Request construction if the src body is null.

LayoutTests/http/tests/fetch/script-tests/request.js

Index: LayoutTests/http/tests/fetch/script-tests/request.js
diff --git a/LayoutTests/http/tests/fetch/script-tests/request.js b/LayoutTests/http/tests/fetch/script-tests/request.js
index 44ef797bf80e9f255a731fae91c734315fbbf0ce..f0aacb885a4837b6fcb75a356d5a414055e14331 100644
--- a/LayoutTests/http/tests/fetch/script-tests/request.js
+++ b/LayoutTests/http/tests/fetch/script-tests/request.js
@@ -272,9 +272,10 @@ test(function() {
     assert_false(req.bodyUsed,
                  'Request should not be flagged as used if it has not been ' +
                  'consumed.');
+    // See https://crbug.com/501195.
     var req2 = new Request(req);
-    assert_false(req.bodyUsed,
-                'Request should not be flagged as used if it does not have' +
+    assert_true(req.bodyUsed,
+                'Request should be flagged as used if it does not have' +
                 'body.');
     assert_false(req2.bodyUsed,
                  'Request should not be flagged as used if it has not been ' +
@@ -292,11 +293,11 @@ test(function() {
     assert_false(req2.bodyUsed,
                  'Request should not be flagged as used if it has not been ' +
                  'consumed.');
-    // Now we can create a Request from |req|, because creating |req2| from
-    // |req| sets |req|'s body to null as specified.
-    var req3 = new Request(req);
-    assert_true(req.bodyUsed,
-                'Request should be flagged as used if it has been consumed.');
+    // See https://crbug.com/501195.
+    assert_throws(
+      {name: 'TypeError'},
+      function() { new Request(req); },
+      'Request construction should throw if used.');
   }, 'Request construction without body behavior regardning "bodyUsed"');
 
 test(function() {