Add some support for the code-point code-unit distinction.

tests/utils/utf8_test.dart

Index: tests/utils/utf8_test.dart
diff --git a/tests/utils/utf8_test.dart b/tests/utils/utf8_test.dart
index 541f101b3778b02b1a0ee1db8ed80670572d48da..b92d5aaab0eec67d4e44ba29f34b66c20f0b274f 100644
--- a/tests/utils/utf8_test.dart
+++ b/tests/utils/utf8_test.dart
@@ -7,8 +7,6 @@ import 'dart:utf';
 
 String decode(List<int> bytes) => decodeUtf8(bytes);
 
-bool isRunningOnJavaScript() => identical(1, 1.0);
-
 main() {
   // Google favorite: "Îñţérñåţîöñåļîžåţîờñ".
   String string = decode([0xc3, 0x8e, 0xc3, 0xb1, 0xc5, 0xa3, 0xc3, 0xa9, 0x72,
@@ -37,14 +35,12 @@ main() {
                    0xb2, 0xe0, 0xa5, 0x88]);
   Expect.stringEquals("िसवा अणामालै", string);
 
-  if (!isRunningOnJavaScript()) {
-    // DESERET CAPITAL LETTER BEE, unicode 0x10412(0xD801+0xDC12)
-    // UTF-8: F0 90 90 92
-    string = decode([0xf0, 0x90, 0x90, 0x92]);
-    Expect.stringEquals("𐐒", string);
-  } else {
-    print('Skipping non-BMP character test');
-  }
+  // DESERET CAPITAL LETTER BEE, unicode 0x10412(0xD801+0xDC12)
+  // UTF-8: F0 90 90 92
+  string = decode([0xf0, 0x90, 0x90, 0x92]);
+  Expect.equals(string.length, 2);
+  Expect.equals("𐐒".length, 2);
+  Expect.stringEquals("𐐒", string);
 
   // TODO(ahe): Add tests of bad input.
 }