Fix Unicode issues in dart2js and dart2dart.

sdk/lib/_internal/compiler/implementation/lib/js_helper.dart

 // Copyright (c) 2012, 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.
 
 library _js_helper;
 
 import 'dart:collection';
 
 part 'constant_map.dart';
 part 'native_helper.dart';
@@ skipping 517 matching lines @@
     if ((length is !int) || (length < 0)) {
       throw new ArgumentError(length);
     }
     var result = JS('=List', r'new Array(#)', length);
     JS('void', r'#.fixed$length = #', result, true);
     return result;
   }
 
   static num dateNow() => JS('num', r'Date.now()');
 
+  static stringFromCodePoints(codePoints) {
+    List<int> a = <int>[];
+    for (var i in codePoints) {
+      if (i is !int) throw new ArgumentError(i);
+      if (i <= 0xffff) {
+        JS('void', r'#.push(#)', a, i);

[floitsch, 2012/11/21 16:16:50]

a.add(i) should be fine. We know the type of the array so this should be
compiled perfectly.

[erikcorry, 2012/11/22 12:42:15]

It's not fine, but i changed it back to just use add(), and I will file a
separate bug to fix that.

+      } else if (i <= 0x10ffff) {
+        JS('void', r'#.push(0xd800 + ((((#) >> 10) & 0x3ff)))', a, i - 0x10000);
+        JS('void', r'#.push(#)', a, 0xdc00 + (i & 0x3ff));
+      } else {
+        throw new ArgumentError(i);
+      }
+    }
+    return JS('String', r'String.fromCharCode.apply(#, #)', null, a);
+  }
+
   static String stringFromCharCodes(charCodes) {
     for (var i in charCodes) {
       if (i is !int) throw new ArgumentError(i);
+      if (i < 0) throw new ArgumentError(i);
+      if (i > 0xffff) return stringFromCodePoints(charCodes);
     }
     return JS('String', r'String.fromCharCode.apply(#, #)', null, charCodes);
   }
 
   static String getTimeZoneName(receiver) {
     // When calling toString on a Date it will emit the timezone in parenthesis.
     // Example: "Wed May 16 2012 21:13:00 GMT+0200 (CEST)".
     // We extract this name using a regexp.
     var d = lazyAsJsDate(receiver);
     return JS('String', r'/\((.*)\)/.exec(#.toString())[1]', d);
@@ skipping 985 matching lines @@
     return typeName == other.typeName;
   }
 }
 
 String getRuntimeTypeString(var object) {
   var typeInfo = JS('var', r'#.builtin$typeInfo', object);
   return JS('String', r'#.runtimeType', typeInfo);
 }
 
 createRuntimeType(String name) => new TypeImpl(name);