[Fetch] Request.clone() should reflect body consumption.

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

Index: LayoutTests/http/tests/fetch/script-tests/response.js
diff --git a/LayoutTests/http/tests/fetch/script-tests/response.js b/LayoutTests/http/tests/fetch/script-tests/response.js
index b3fc72ef8f75f7960a894cb64fa57cbd5a80decb..5ba901a5ad0e0f8abc69ad0df26a80ffa37551d9 100644
--- a/LayoutTests/http/tests/fetch/script-tests/response.js
+++ b/LayoutTests/http/tests/fetch/script-tests/response.js
@@ -355,6 +355,11 @@ promise_test(function(t) {
     return Promise.all([res.text(), clone.text()]).then(function(r) {
         assert_equals(r[0], 'hello');
         assert_equals(r[1], 'hello');
+        return Promise.all([res.text(), clone.text(), res.clone().text()]);
+      }).then(function(r) {
+        assert_equals(r[0], '');
+        assert_equals(r[1], '');
+        assert_equals(r[2], '');
       });
   }, 'Clone on Response (text)');
 
@@ -371,6 +376,11 @@ promise_test(function(t) {
     return Promise.all([consume(reader1), consume(reader2)]).then(function(r) {
         assert_equals(decode(r[0]), 'hello');
         assert_equals(decode(r[1]), 'hello');
+        return Promise.all([res.text(), clone.text(), res.clone().text()]);
+      }).then(function(r) {
+        assert_equals(r[0], '');
+        assert_equals(r[1], '');
+        assert_equals(r[2], '');
       });
   }, 'Clone on Response (manual read)');