Fix Unicode issues in dart2js and dart2dart.

sdk/lib/utf/utf16.dart

Index: sdk/lib/utf/utf16.dart
diff --git a/sdk/lib/utf/utf16.dart b/sdk/lib/utf/utf16.dart
index d1bd012fc5992a3d4e33d684ad9515dd897d625f..a99eadae27e6b4a939f80342531c72708ec94ed3 100644
--- a/sdk/lib/utf/utf16.dart
+++ b/sdk/lib/utf/utf16.dart
@@ -62,15 +62,8 @@ String decodeUtf16(List<int> bytes, [int offset = 0, int length,
   Utf16BytesToCodeUnitsDecoder decoder = new Utf16BytesToCodeUnitsDecoder(bytes,
       offset, length, replacementCodepoint);
   List<int> codeunits = decoder.decodeRest();
-  // TODO is16BitCodeUnit() is used to work around a bug with dart2js
-  // (http://code.google.com/p/dart/issues/detail?id=1357). Consider
-  // removing after this issue is resolved.
-  if (_is16BitCodeUnit()) {
-    return new String.fromCharCodes(codeunits);
-  } else {
-    return new String.fromCharCodes(
-        _utf16CodeUnitsToCodepoints(codeunits, 0, null, replacementCodepoint));
-  }
+  return new String.fromCharCodes(
+      _utf16CodeUnitsToCodepoints(codeunits, 0, null, replacementCodepoint));
 }
 
 /**
@@ -85,15 +78,8 @@ String decodeUtf16be(List<int> bytes, [int offset = 0, int length,
     int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) {
   List<int> codeunits = (new Utf16beBytesToCodeUnitsDecoder(bytes, offset,
       length, stripBom, replacementCodepoint)).decodeRest();
-  // TODO is16BitCodeUnit() is used to work around a bug with dart2js
-  // (http://code.google.com/p/dart/issues/detail?id=1357). Consider
-  // removing after this issue is resolved.
-  if (_is16BitCodeUnit()) {
-    return new String.fromCharCodes(codeunits);
-  } else {
-    return new String.fromCharCodes(
-        _utf16CodeUnitsToCodepoints(codeunits, 0, null, replacementCodepoint));
-  }
+  return new String.fromCharCodes(
+      _utf16CodeUnitsToCodepoints(codeunits, 0, null, replacementCodepoint));
 }
 
 /**
@@ -108,15 +94,8 @@ String decodeUtf16le(List<int> bytes, [int offset = 0, int length,
     int replacementCodepoint = UNICODE_REPLACEMENT_CHARACTER_CODEPOINT]) {
   List<int> codeunits = (new Utf16leBytesToCodeUnitsDecoder(bytes, offset,
       length, stripBom, replacementCodepoint)).decodeRest();
-  // TODO is16BitCodeUnit() is used to work around a bug with dart2js
-  // (http://code.google.com/p/dart/issues/detail?id=1357). Consider
-  // removing after this issue is resolved.
-  if (_is16BitCodeUnit()) {
-    return new String.fromCharCodes(codeunits);
-  } else {
-    return new String.fromCharCodes(
-        _utf16CodeUnitsToCodepoints(codeunits, 0, null, replacementCodepoint));
-  }
+  return new String.fromCharCodes(
+      _utf16CodeUnitsToCodepoints(codeunits, 0, null, replacementCodepoint));
 }
 
 /**
@@ -198,14 +177,7 @@ bool hasUtf16leBom(List<int> utf16EncodedBytes, [int offset = 0, int length]) {
 }
 
 List<int> _stringToUtf16CodeUnits(String str) {
-  // TODO is16BitCodeUnit() is used to work around a bug with dart2js
-  // (http://code.google.com/p/dart/issues/detail?id=1357). Consider
-  // removing after this issue is resolved.
-  if (_is16BitCodeUnit()) {
-    return str.charCodes;
-  } else {
-    return _codepointsToUtf16CodeUnits(str.charCodes);
-  }
+  return _codepointsToUtf16CodeUnits(str.charCodes);
 }
 
 typedef _ListRangeIterator _CodeUnitsProvider();