Refactoring of string literals. Implement static string addition.

frog/leg/util/characters.dart

 // Copyright (c) 2011, 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("characters");
 
 final int $EOF = 0;
 final int $STX = 2;
+final int $BS  = 8;
 final int $TAB = 9;
 final int $LF = 10;
+final int $VTAB = 11;
+final int $FF = 12;
 final int $CR = 13;
 final int $SPACE = 32;
 final int $BANG = 33;
 final int $DQ = 34;
 final int $HASH = 35;
 final int $$ = 36;
 final int $PERCENT = 37;
 final int $AMPERSAND = 38;
 final int $SQ = 39;
 final int $OPEN_PAREN = 40;
@@ skipping 101 matching lines @@
   assert(isHexDigit(hexDigit));
   // hexDigit is one of '0'..'9', 'A'..'F' and 'a'..'f'.
   if (hexDigit <= $9) return hexDigit - $0;
   return (hexDigit | ($a ^ $A)) - ($a - 10);
 }
 
 bool isUnicodeScalarValue(int value) {
   return value < $FIRST_SURROGATE ||
       (value > $LAST_SURROGATE && value <= $LAST_CODE_POINT);
 }