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

tests/corelib/string_trim2_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // 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";
 
 const WHITESPACE = const [
   0x09,
   0x0A,
   0x0B,
   0x0C,
   0x0D,
   0x20,
   0x85,
   0xA0,
   0x1680,
+  0x180E,
   0x2000,
   0x2001,
   0x2002,
   0x2003,
   0x2004,
   0x2005,
   0x2006,
   0x2007,
   0x2008,
   0x2009,
@@ skipping 12 matching lines @@
     var c = new String.fromCharCode(ws);
     Expect.equals("", c.trim(), "$name");
     Expect.equals("a", ("a" + c).trim(), "a-$name");
     Expect.equals("a", (c + "a").trim(), "$name-a");
     Expect.equals("a", (c + c + "a" + c + c).trim(), "$name around");
     Expect.equals("a" + c + "a", (c + c + "a" + c + "a" + c + c).trim(),
                   "$name many");
   }
   Expect.equals("", new String.fromCharCodes(WHITESPACE).trim(), "ALL");
 }