Enables codegen support in polymer

pkg/code_transformers/lib/src/resolver.dart

Index: pkg/code_transformers/lib/src/resolver.dart
diff --git a/pkg/code_transformers/lib/src/resolver.dart b/pkg/code_transformers/lib/src/resolver.dart
index fac1aac265c2d1175a30c5108a6f2d3a9c6860ea..95f5b1c0c028029f57180975e915236b2acf7daf 100644
--- a/pkg/code_transformers/lib/src/resolver.dart
+++ b/pkg/code_transformers/lib/src/resolver.dart
@@ -6,6 +6,8 @@ library code_transformer.src.resolver;
 
 import 'dart:async';
 
+import 'package:analyzer/src/generated/ast.dart' show Expression;
+import 'package:analyzer/src/generated/constant.dart' show EvaluationResult;
 import 'package:analyzer/src/generated/element.dart';
 import 'package:barback/barback.dart';
 import 'package:source_maps/refactor.dart';
@@ -68,6 +70,11 @@ abstract class Resolver {
   /// potential library name conflicts the name is not guaranteed to be unique.
   Element getLibraryFunction(String functionName);
 
+  /// Gets the result of evaluating the constant [expression] in the context of
+  /// a [library].
+  EvaluationResult evaluateConstant(
+      LibraryElement library, Expression expression);
+
   /// Gets an URI appropriate for importing the specified library.
   ///
   /// Returns null if the library cannot be imported via an absolute URI or