Fix all strong mode errors and warnings.

lib/src/tokenizer.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.
 
 part of csslib.parser;
 
 class Tokenizer extends TokenizerBase {
   /** U+ prefix for unicode characters. */
   final UNICODE_U = 'U'.codeUnitAt(0);
   final UNICODE_LOWER_U = 'u'.codeUnitAt(0);
@@ skipping 242 matching lines @@
           ? TokenKind.IMPORTANT
           : -1;
     }
 
     return tokId >= 0 ? tokId : TokenKind.IDENTIFIER;
   }
 
   Token finishIdentifier() {
     // If we encounter an escape sequence, remember it so we can post-process
     // to unescape.
-    var chars = [];
+    var chars = <int>[];
 
     // backup so we can start with the first character
     int validateFrom = _index;
     _index = _startIndex;
     while (_index < _text.length) {
       int ch = _text.codeUnitAt(_index);
 
       // If the previous character was "\" we need to escape. T
       // http://www.w3.org/TR/CSS21/syndata.html#characters
       // if followed by hexadecimal digits, create the appropriate character.
@@ skipping 173 matching lines @@
         // http://www.w3.org/TR/CSS21/syndata.html#characters
         // Also, escaped character should be allowed.
         c == 95 /*_*/ || c >= 0xA0 || c == 92 /*\*/);
   }
 
   /** Pseudo function expressions identifiers can't have a minus sign. */
   static bool isIdentifierPartExpr(int c) {
     return (isIdentifierStartExpr(c) || isDigit(c));
   }
 }