Add CoreTypes interface.

pkg/compiler/lib/src/core_types.dart

Index: pkg/compiler/lib/src/core_types.dart
diff --git a/pkg/compiler/lib/src/core_types.dart b/pkg/compiler/lib/src/core_types.dart
new file mode 100644
index 0000000000000000000000000000000000000000..738cf4118bfaeb8eb1e5b938f90c453b4231d0cf
--- /dev/null
+++ b/pkg/compiler/lib/src/core_types.dart
@@ -0,0 +1,40 @@
+// 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.type_system;
+
+import 'dart_types.dart';
+
+/// The core types in Dart.
+abstract class CoreTypes {
+  /// The `bool` type defined in 'dart:core'.
+  InterfaceType get boolType;
+
+  /// The `bool` type defined in 'dart:core'.
+  InterfaceType get numType;
+
+  /// The `int` type defined in 'dart:core'.
+  InterfaceType get intType;
+
+  /// The `double` type defined in 'dart:core'.
+  InterfaceType get doubleType;
+
+  /// The `String` type defined in 'dart:core'.
+  InterfaceType get stringType;
+
+  /// The `Function` type defined in 'dart:core'.
+  InterfaceType get functionType;
+
+  /// The `Null` type defined in 'dart:core'.
+  InterfaceType get nullType;
+
+  /// Returns an instance of the `List` type defined in 'dart:core' with
+  /// [elementType] as its type argument.
+  InterfaceType listType([DartType elementType = const DynamicType()]);
+
+  /// Returns an instance of the `Map` type defined in 'dart:core' with
+  /// [keyType] and [valueType] as its type arguments.
+  InterfaceType mapType([DartType keyType = const DynamicType(),
+                         DartType valueType = const DynamicType()]);
+}