Implement cascaded calls.

lib/compiler/implementation/scanner/token.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.
 
 final int EOF_TOKEN = 0;
 
 final int KEYWORD_TOKEN = $k;
 final int IDENTIFIER_TOKEN = $a;
 final int DOUBLE_TOKEN = $d;
 final int INT_TOKEN = $i;
@@ skipping 230 matching lines @@
 
 // TODO(ahe): The following are not tokens in Dart.
 final PrecedenceInfo BACKPING_INFO =
   const PrecedenceInfo(const SourceString('`'), 0, BACKPING_TOKEN);
 final PrecedenceInfo BACKSLASH_INFO =
   const PrecedenceInfo(const SourceString('\\'), 0, BACKSLASH_TOKEN);
 final PrecedenceInfo PERIOD_PERIOD_PERIOD_INFO =
   const PrecedenceInfo(const SourceString('...'), 0,
                        PERIOD_PERIOD_PERIOD_TOKEN);
 
-// TODO(ahe): This might become a token.
+/**
+ * The cascade operator has the lowest precedence of any operator.
+ */
+final int CASCADE_PRECEDENCE = 1;
 final PrecedenceInfo PERIOD_PERIOD_INFO =
-  const PrecedenceInfo(const SourceString('..'), 0, PERIOD_PERIOD_TOKEN);
+  const PrecedenceInfo(const SourceString('..'), CASCADE_PRECEDENCE,
+                       PERIOD_PERIOD_TOKEN);
 
 final PrecedenceInfo BANG_INFO =
   const PrecedenceInfo(const SourceString('!'), 0, BANG_TOKEN);
 final PrecedenceInfo COLON_INFO =
   const PrecedenceInfo(const SourceString(':'), 0, COLON_TOKEN);
 final PrecedenceInfo INDEX_INFO =
   const PrecedenceInfo(const SourceString('[]'), 0, INDEX_TOKEN);
 final PrecedenceInfo MINUS_MINUS_INFO =
   const PrecedenceInfo(const SourceString('--'), POSTFIX_PRECEDENCE,
                        MINUS_MINUS_TOKEN);
@@ skipping 165 matching lines @@
 
 final PrecedenceInfo STRING_INTERPOLATION_INFO =
   const PrecedenceInfo(const SourceString('\${'), 0,
                        STRING_INTERPOLATION_TOKEN);
 
 final PrecedenceInfo HEXADECIMAL_INFO =
   const PrecedenceInfo(const SourceString('hexadecimal'), 0, HEXADECIMAL_TOKEN);
 
 // For reporting lexical errors.
 final PrecedenceInfo ERROR_INFO =
-  const PrecedenceInfo(const SourceString('?'), 0, UNKNOWN_TOKEN);
+  const PrecedenceInfo(const SourceString('?'), 0, UNKNOWN_TOKEN);