Check for compile-time constants in DartCompiler

compiler/java/com/google/dart/compiler/ast/DartExpression.java

 // 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.
 
 package com.google.dart.compiler.ast;
 
+import com.google.dart.compiler.type.Type;
+
 /**
  * Abstract base class for Dart expressions.
  */
 public abstract class DartExpression extends DartNode {
+  Type type;
 
   public boolean isAssignable() {
     // By default you cannot assign to expressions.
     return false;
   }
 
   @Override
   public DartExpression getNormalizedNode() {
     return (DartExpression) super.getNormalizedNode();
   }
+
+  @Override
+  public void setType(Type type) {
+   this.type = type;
+  }
+
+  @Override
+  public Type getType() {
+    return type;
+  }
 }