Revert "Remove U+180E from whitespace in js_runtime and tests"

tests/corelib_strong/string_trimlr_test.dart

Index: tests/corelib_strong/string_trimlr_test.dart
diff --git a/tests/corelib_strong/string_trimlr_test.dart b/tests/corelib_strong/string_trimlr_test.dart
index 68afce0f147782f9c104298a63de59ae2e4c925a..cf47ffc6a8b9fbb3642ba9c852182c27dedb1e5f 100644
--- a/tests/corelib_strong/string_trimlr_test.dart
+++ b/tests/corelib_strong/string_trimlr_test.dart
@@ -4,12 +4,13 @@
 
 import "package:expect/expect.dart";
 
-// Characters with Whitespace property (Unicode 6.3).
+// Characters with Whitespace property (Unicode 6.2).
 // 0009..000D    ; White_Space # Cc       <control-0009>..<control-000D>
 // 0020          ; White_Space # Zs       SPACE
 // 0085          ; White_Space # Cc       <control-0085>
 // 00A0          ; White_Space # Zs       NO-BREAK SPACE
 // 1680          ; White_Space # Zs       OGHAM SPACE MARK
+// 180E          ; White_Space # Zs       MONGOLIAN VOWEL SEPARATOR
 // 2000..200A    ; White_Space # Zs       EN QUAD..HAIR SPACE
 // 2028          ; White_Space # Zl       LINE SEPARATOR
 // 2029          ; White_Space # Zp       PARAGRAPH SEPARATOR
@@ -28,6 +29,7 @@ const WHITESPACE = const [
   0x85,
   0xA0,
   0x1680,
+  0x180E,
   0x2000,
   0x2001,
   0x2002,