Add support for the new function-type syntax.

pkg/compiler/lib/src/dart_types.dart

Index: pkg/compiler/lib/src/dart_types.dart
diff --git a/pkg/compiler/lib/src/dart_types.dart b/pkg/compiler/lib/src/dart_types.dart
index b151ed99b75193dfdc0ca3a52022f190c841e35f..ffc4ffe48bd583797a248196235d43f6a25efc27 100644
--- a/pkg/compiler/lib/src/dart_types.dart
+++ b/pkg/compiler/lib/src/dart_types.dart
@@ -615,6 +615,16 @@ class FunctionType extends DartType {
         optionalParameterTypes, namedParameters, namedParameterTypes);
   }
 
+  factory FunctionType.generalized(
+      DartType returnType,
+      List<DartType> parameterTypes,
+      List<DartType> optionalParameterTypes,
+      List<String> namedParameters,
+      List<DartType> namedParameterTypes) {
+    return new FunctionType.internal(null, returnType, parameterTypes,
+        optionalParameterTypes, namedParameters, namedParameterTypes);
+  }
+
   FunctionType.internal(FunctionTypedElement this.element,
       [DartType returnType = const DynamicType(),
       List<DartType> parameterTypes = const <DartType>[],