[Fetch] Remove Request.body.

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

 if (self.importScripts) {
   importScripts('../resources/fetch-test-helpers.js');
 }
 
 var URL = 'https://www.example.com/test.html';
 
 function size(headers) {
   var count = 0;
   for (var header of headers) {
     ++count;
@@ skipping 671 matching lines @@
                            body: new Blob([''], {type: 'Text/Plain'})});
     req.headers.set('Content-Type', 'Text/Html');
     return req.blob()
       .then(function(blob) {
           assert_equals(blob.type, 'text/plain');
           assert_equals(req.headers.get('Content-Type'), 'Text/Html');
         });
   },
   'MIME type unchanged if headers are modified after Request() constructor');
 
-// The following two tests follow different code paths in Body::readAsync().
 promise_test(function(t) {
     var req = new Request('http://localhost/',
                           {method: 'POST',
                            body: new Blob([''], {type: 'Text/Plain'}),
                            headers: [['Content-Type', 'Text/Html']]});
     return req.blob()
       .then(function(blob) {
           assert_equals(blob.type, 'text/html');
           assert_equals(req.headers.get('Content-Type'), 'Text/Html');
         });
   }, 'Extract a MIME type (1)');
 
-promise_test(function(t) {
-    var req = new Request('http://localhost/',
-                          {method: 'POST',
-                           body: new Blob([''], {type: 'Text/Plain'}),
-                           headers: [['Content-Type', 'Text/Html']]});
-    req.body.cancel();
-    return req.blob()
-      .then(function(blob) {
-          assert_equals(blob.type, 'text/html');
-          assert_equals(req.headers.get('Content-Type'), 'Text/Html');
-        });
-  }, 'Extract a MIME type (2)');
-
 done();