Update yield warnings.

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
index 291978d9e67ef9d8b1608530b922a0f85320e0d8..ba71b3f43de43bb26b60a1f571696174bf9b3b84 100644
--- a/pkg/compiler/lib/src/core_types.dart
+++ b/pkg/compiler/lib/src/core_types.dart
@@ -40,4 +40,16 @@ abstract class CoreTypes {
   /// [keyType] and [valueType] as its type arguments.
   InterfaceType mapType([DartType keyType = const DynamicType(),
                          DartType valueType = const DynamicType()]);
+
+  /// Returns an instance of the `Iterable` type defined in 'dart:core' with
+  /// [elementType] as its type argument.
+  InterfaceType iterableType([DartType elementType = const DynamicType()]);
+
+  /// Returns an instance of the `Future` type defined in 'dart:async' with
+  /// [elementType] as its type argument.
+  InterfaceType futureType([DartType elementType = const DynamicType()]);
+
+  /// Returns an instance of the `Stream` type defined in 'dart:async' with
+  /// [elementType] as its type argument.
+  InterfaceType streamType([DartType elementType = const DynamicType()]);
 }