[Fetch API] Put body members directly on Response/Request

LayoutTests/http/tests/serviceworker/resources/response-content-worker.js

 importScripts('worker-test-harness.js');
 
 promise_test(function() {
     var response = new Response('test string');
     assert_equals(
       response.headers.get('Content-Type'),
       'text/plain;charset=UTF-8',
       'A Response constructed with a string should have a Content-Type.');
-    return response.body.asText()
+    return response.text()
       .then(function(text) {
           assert_equals(text, 'test string',
             'Response body text should match the string on construction.');
         });
   }, 'Behavior of Response with string content.');
 
 promise_test(function() {
     var intView = new Int32Array([0, 1, 2, 3, 4, 55, 6, 7, 8, 9]);
     var buffer = intView.buffer;
 
     var response = new Response(buffer);
     assert_false(response.headers.has('Content-Type'),
       'A Response constructed with ArrayBuffer should not have a content type.');
-    return response.body.asArrayBuffer()
+    return response.arrayBuffer()
       .then(function(buffer) {
           var resultIntView = new Int32Array(buffer);
           assert_array_equals(
             resultIntView, [0, 1, 2, 3, 4, 55, 6, 7, 8, 9],
             'Response body ArrayBuffer should match ArrayBuffer ' +
             'it was constructed with.');
         });
   }, 'Behavior of Response with ArrayBuffer content.');
 
 promise_test(function() {
     var intView = new Int32Array([0, 1, 2, 3, 4, 55, 6, 7, 8, 9]);
 
     var response = new Response(intView);
     assert_false(response.headers.has('Content-Type'),
       'A Response constructed with ArrayBufferView ' +
       'should not have a content type.');
-    return response.body.asArrayBuffer()
+    return response.arrayBuffer()
       .then(function(buffer) {
           var resultIntView = new Int32Array(buffer);
           assert_array_equals(
             resultIntView, [0, 1, 2, 3, 4, 55, 6, 7, 8, 9],
             'Response body ArrayBuffer should match ArrayBufferView ' +
             'it was constructed with.');
         });
   }, 'Behavior of Response with ArrayBufferView content without a slice.');
 
 promise_test(function() {
     var intView = new Int32Array([0, 1, 2, 3, 4, 55, 6, 7, 8, 9]);
     var slice = intView.subarray(1, 4);  // Should be [1, 2, 3]
     var response = new Response(slice);
     assert_false(response.headers.has('Content-Type'),
       'A Response constructed with ArrayBufferView ' +
       'should not have a content type.');
-    return response.body.asArrayBuffer()
+    return response.arrayBuffer()
       .then(function(buffer) {
           var resultIntView = new Int32Array(buffer);
           assert_array_equals(
             resultIntView, [1, 2, 3],
             'Response body ArrayBuffer should match ArrayBufferView ' +
             'slice it was constructed with.');
         });
   }, 'Behavior of Response with ArrayBufferView content with a slice.');