Non-fatal errors in compile-time constants.

dart/pkg/compiler/lib/src/constants/expressions.dart

 // Copyright (c) 2014, 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 dart2js.constants.expressions;
 
 import '../dart2jslib.dart' show assertDebugMode;
 import '../dart_types.dart';
 import '../elements/elements.dart' show
     Element,
@@ skipping 27 matching lines @@
     return printer.toString();
   }
 
   String toString() {
     assertDebugMode('Use ConstantExpression.getText() instead of '
                     'ConstantExpression.toString()');
     return getText();
   }
 }
 
+/// A synthetic constant used to recover from errors.
+class ErroneousConstantExpression extends ConstantExpression {
+  final PrimitiveConstantValue value = new NullConstantValue();
+
+  ErroneousConstantExpression();
+
+  accept(ConstantExpressionVisitor visitor, [context]) {
+    // Do nothing. This is an error.
+  }
+}
+
 /// Boolean, int, double, string, or null constant.
 class PrimitiveConstantExpression extends ConstantExpression {
   final PrimitiveConstantValue value;
 
   PrimitiveConstantExpression(this.value) {
     assert(value != null);
   }
 
   accept(ConstantExpressionVisitor visitor, [context]) {
     return visitor.visitPrimitive(this, context);
@@ skipping 390 matching lines @@
   void visitConditional(ConditionalConstantExpression exp, [_]) {
     write(exp, exp.condition, leftAssociative: false);
     sb.write(' ? ');
     write(exp, exp.trueExp);
     sb.write(' : ');
     write(exp, exp.falseExp);
   }
 
   String toString() => sb.toString();
 }