Add ConstantExpression.evaluate.

pkg/compiler/lib/src/js_backend/constant_system_javascript.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.
 
 library dart2js.constant_system.js;
 
 import '../constants/constant_system.dart';
 import '../constants/values.dart';
 import '../constant_system_dart.dart';
 import '../dart_types.dart';
@@ skipping 222 matching lines @@
           !constant.isMinusZero) {
         int intValue = doubleValue.truncate();
         if (intValue == doubleValue) {
           return new IntConstantValue(intValue);
         }
       }
     }
     return constant;
   }
 
-  NumConstantValue createInt(int i)
-      => convertToJavaScriptConstant(new IntConstantValue(i));
+  @override
+  NumConstantValue createInt(int i) {
+    return convertToJavaScriptConstant(new IntConstantValue(i));
+  }
+
   NumConstantValue createInt32(int i) => new IntConstantValue(i & BITS32);
   NumConstantValue createDouble(double d)
       => convertToJavaScriptConstant(new DoubleConstantValue(d));
   StringConstantValue createString(DartString string) {
     return new StringConstantValue(string);
   }
   BoolConstantValue createBool(bool value) => new BoolConstantValue(value);
   NullConstantValue createNull() => new NullConstantValue();
 
+
+  @override
+  ListConstantValue createList(InterfaceType type,
+                               List<ConstantValue> values) {
+    return new ListConstantValue(type, values);
+  }
+
+  @override
+  ConstantValue createType(Compiler compiler, DartType type) {
+    return new TypeConstantValue(
+        type, compiler.backend.typeImplementation.computeType(compiler));
+  }
+
   // Integer checks don't verify that the number is not -0.0.
   bool isInt(ConstantValue constant) => constant.isInt || constant.isMinusZero;
   bool isDouble(ConstantValue constant)
       => constant.isDouble && !constant.isMinusZero;
   bool isString(ConstantValue constant) => constant.isString;
   bool isBool(ConstantValue constant) => constant.isBool;
   bool isNull(ConstantValue constant) => constant.isNull;
 
   bool isSubtype(DartTypes types, DartType s, DartType t) {
     // At runtime, an integer is both an integer and a double: the
@@ skipping 94 matching lines @@
       result.add(keyList);
     } else {
       // Add the keys individually to avoid generating an unused list constant
       // for the keys.
       result.addAll(keys);
     }
     result.addAll(values);
     return result;
   }
 }