Static members are not visible in subclasses

frog/tokenizer.dart

Index: frog/tokenizer.dart
===================================================================
--- frog/tokenizer.dart	(revision 6666)
+++ frog/tokenizer.dart	(working copy)
@@ -167,7 +167,7 @@
 
   void eatDigits() {
     while (_index < _text.length) {
-      if (isDigit(_text.charCodeAt(_index))) {
+      if (TokenizerHelpers.isDigit(_text.charCodeAt(_index))) {
         _index++;
       } else {
         return;
@@ -230,7 +230,7 @@
     if (_peekChar() == 46/*.*/) {
       // Handle the case of 1.toString().
       _nextChar();
-      if (isDigit(_peekChar())) {
+      if (TokenizerHelpers.isDigit(_peekChar())) {
         eatDigits();
         return finishNumberExtra(TokenKind.DOUBLE);
       } else {
@@ -248,7 +248,7 @@
       _maybeEatChar(43/*+*/);
       eatDigits();
     }
-    if (_peekChar() != 0 && isIdentifierStart(_peekChar())) {
+    if (_peekChar() != 0 && TokenizerHelpers.isIdentifierStart(_peekChar())) {
       _nextChar();
       return _errorToken("illegal character in number");
     }
@@ -443,7 +443,7 @@
   }
 
   Token finishDot() {
-    if (isDigit(_peekChar())) {
+    if (TokenizerHelpers.isDigit(_peekChar())) {
       eatDigits();
       return finishNumberExtra(TokenKind.DOUBLE);
     } else {
@@ -459,14 +459,14 @@
             @"illegal character after $ in string interpolation");
       }
       while (_index < _text.length) {
-        if (!isInterpIdentifierPart(_text.charCodeAt(_index++))) {
+        if (!TokenizerHelpers.isInterpIdentifierPart(_text.charCodeAt(_index++))) {
           _index--;
           break;
         }
       }
     } else {
       while (_index < _text.length) {
-        if (!isIdentifierPart(_text.charCodeAt(_index++))) {
+        if (!TokenizerHelpers.isIdentifierPart(_text.charCodeAt(_index++))) {
           _index--;
           break;
         }