Allow constant folding of && and ||.

frog/leg/compile_time_constants.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.
 
 class Constant implements Hashable {
   const Constant();
 
   bool isNull() => false;
   bool isBool() => false;
   bool isTrue() => false;
@@ skipping 860 matching lines @@
           break;
         case "|":
           folded = const BitOrOperation().fold(left, right);
           break;
         case "&":
           folded = const BitAndOperation().fold(left, right);
           break;
         case "^":
           folded = const BitXorOperation().fold(left, right);
           break;
+        case "||":
+          folded = const BooleanOr().fold(left, right);
+          break;
+        case "&&":
+          folded = const BooleanAnd().fold(left, right);
+          break;
         case "<<":
           folded = const ShiftLeftOperation().fold(left, right);
           break;
         case ">>":
           folded = const ShiftRightOperation().fold(left, right);
           break;
         case "<":
           folded = const LessOperation().fold(left, right);
           break;
         case "<=":
@@ skipping 169 matching lines @@
     return node.expression.accept(this);
   }
 
   error(Node node) {
     // TODO(floitsch): get the list of constants that are currently compiled
     // and present some kind of stack-trace.
     MessageKind kind = MessageKind.NOT_A_COMPILE_TIME_CONSTANT;
     compiler.reportError(node, new CompileTimeConstantError(kind, const []));
   }
 }