Revert "Temporarily expose createObjectUrl/revokeObjectUrl on window."

tests/html/url_test.dart

Index: tests/html/url_test.dart
diff --git a/tests/html/url_test.dart b/tests/html/url_test.dart
index c8b16c31e7d200b55ea8a9730af6070d64cec02b..f6527bbb71e392ca2fa999f4cf9bd7fdf15d2c52 100644
--- a/tests/html/url_test.dart
+++ b/tests/html/url_test.dart
@@ -36,7 +36,7 @@ main() {
   group('blob', () {
     test('createObjectUrl', () {
       var blob = createImageBlob();
-      var url = window.createObjectUrl(blob);
+      var url = DOMURL.createObjectURL(blob);
       expect(url.length, greaterThan(0));
       expect(url.startsWith('blob:'));
 
@@ -52,9 +52,9 @@ main() {
       img.src = url;
     });
 
-    test('revokeObjectUrl', () {
+    test('revokeObjectURL', () {
       var blob = createImageBlob();
-      var url = window.createObjectUrl(blob);
+      var url = DOMURL.createObjectURL(blob);
       expect(url.startsWith('blob:'));
       DOMURL.revokeObjectURL(url);