[Fetch] Body consume function should not set bodyUsed flag.

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

 if (self.importScripts) {
   importScripts('../resources/fetch-test-helpers.js');
 }
 
 function size(headers) {
   var count = 0;
   for (var header of headers) {
     ++count;
   }
   return count;
@@ skipping 475 matching lines @@
                            {headers: [['Content-Type', 'Text/Html']]});
     res.body.cancel();
     res = res.clone();
     return res.blob()
       .then(function(blob) {
           assert_equals(blob.type, 'text/html');
           assert_equals(res.headers.get('Content-Type'), 'Text/Html');
         });
   }, 'Extract a MIME type (3)');
 
+promise_test(function(t) {
+    var res = new Response('hello');
+    return res.text().then(function(text) {
+        assert_equals(text, 'hello');
+        return Promise.all([res.text(), res.text()]);
+      }).then(function(texts) {
+        assert_equals(texts[0], '');
+        assert_equals(texts[1], '');
+        return res.body.getReader().read();
+      }).then(function(r) {
+        assert_true(r.done);
+        assert_equals(r.value, undefined);
+      });
+  }, 'Read after text()');
+
 done();