Support percent encoded data URIs in the standalone embedder.

runtime/tests/vm/dart/data_uri_import_test.dart

Index: runtime/tests/vm/dart/data_uri_import_test.dart
diff --git a/tests/language/issue13179_test.dart b/runtime/tests/vm/dart/data_uri_import_test.dart
similarity index 67%
copy from tests/language/issue13179_test.dart
copy to runtime/tests/vm/dart/data_uri_import_test.dart
index 0439ceab895f5925234763b90cb323007bc19b14..2430b9528a85ddd33803096d9639de69de3b83a2 100644
--- a/tests/language/issue13179_test.dart
+++ b/runtime/tests/vm/dart/data_uri_import_test.dart
@@ -2,18 +2,11 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import "package:expect/expect.dart";
-
-int count = 0;
+// foo() => 42;
+import 'data:application/dart;charset=utf-8,foo%28%29%20%3D%3E%2042%3B';
 
-void f([void f([x]) = f]) {
-  count++;
-  if (f != null) {
-    f(null);
-  }
-}
+import "package:expect/expect.dart";
 
 main() {
-  f();
-  Expect.equals(2, count);
-}
+  Expect.equals(42, foo());
+}