Support 'URLSearchParams' as the body of a Request

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

Index: third_party/WebKit/LayoutTests/http/tests/fetch/script-tests/request.js
diff --git a/third_party/WebKit/LayoutTests/http/tests/fetch/script-tests/request.js b/third_party/WebKit/LayoutTests/http/tests/fetch/script-tests/request.js
index 9cd67290e28792a24144c8bca5219acfa0316bcd..fa988b277025184dbf7e5985522a3d5bd6f6175f 100644
--- a/third_party/WebKit/LayoutTests/http/tests/fetch/script-tests/request.js
+++ b/third_party/WebKit/LayoutTests/http/tests/fetch/script-tests/request.js
@@ -595,6 +595,15 @@ async_test(function(t) {
             'Creating a Request with FormData body should success.');
         })
       .then(function() {
+          var params = new URLSearchParams();
+          params.append('sample string', '1234567890');
+          request = new Request(URL, {method: 'POST', body: params});
+          return request.text();
+        })
+      .then(function(result) {
+          assert_equals(result, "sample+string=1234567890");
+        })
+      .then(function() {
           t.done();
         })
       .catch(unreached_rejection(t));