Tests for `void`.

pkg/compiler/lib/src/elements/resolution_types.dart

Index: pkg/compiler/lib/src/elements/resolution_types.dart
diff --git a/pkg/compiler/lib/src/elements/resolution_types.dart b/pkg/compiler/lib/src/elements/resolution_types.dart
index b8ed4fb8c1b169a802d0f2ee00bcee4cae82245f..07850b6985bda6925158d1165b0daa79bd1af90f 100644
--- a/pkg/compiler/lib/src/elements/resolution_types.dart
+++ b/pkg/compiler/lib/src/elements/resolution_types.dart
@@ -25,7 +25,6 @@ enum ResolutionTypeKind {
   TYPE_VARIABLE,
   MALFORMED_TYPE,
   DYNAMIC,
-  VOID,
 }
 
 abstract class ResolutionDartType implements DartType {
@@ -110,7 +109,7 @@ abstract class ResolutionDartType implements DartType {
   bool get isDynamic => kind == ResolutionTypeKind.DYNAMIC;
 
   /// Is [: true :] if this type is the void type.
-  bool get isVoid => kind == ResolutionTypeKind.VOID;
+  bool get isVoid => false;
 
   /// Is [: true :] if this is the type of `Object` from dart:core.
   bool get isObject => false;
@@ -272,10 +271,9 @@ class MethodTypeVariableType extends ResolutionTypeVariableType {
   get containsMethodTypeVariableType => true;
 }
 
-class ResolutionVoidType extends ResolutionDartType implements VoidType {
-  const ResolutionVoidType();
-
-  ResolutionTypeKind get kind => ResolutionTypeKind.VOID;
+class ResolutionVoidType extends ResolutionInterfaceType implements VoidType {
+  ResolutionVoidType(ClassElement objectElement)
+      : super(objectElement);
 
   String get name => 'void';
 
@@ -291,6 +289,9 @@ class ResolutionVoidType extends ResolutionDartType implements VoidType {
     return visitor.visitVoidType(this, argument);
   }
 
+  @override
+  bool get isVoid => true;
+
   String toString() => name;
 
   int get hashCode => 6007;
@@ -642,6 +643,16 @@ class ResolutionFunctionType extends ResolutionDartType
         optionalParameterTypes, namedParameters, namedParameterTypes);
   }
 
+  factory ResolutionFunctionType.generalized(
+      ResolutionDartType returnType,
+      List<ResolutionDartType> parameterTypes,
+      List<ResolutionDartType> optionalParameterTypes,
+      List<String> namedParameters,
+      List<ResolutionDartType> namedParameterTypes) {
+    return new ResolutionFunctionType.internal(null, returnType, parameterTypes,
+        optionalParameterTypes, namedParameters, namedParameterTypes);
+  }
+
   ResolutionFunctionType.internal(FunctionTypedElement this.element,
       [ResolutionDartType returnType = const ResolutionDynamicType(),
       List<ResolutionDartType> parameterTypes = const <ResolutionDartType>[],
@@ -989,7 +1000,7 @@ abstract class BaseDartTypeVisitor<R, A> extends DartTypeVisitor<R, A> {
 
   @override
   R visitVoidType(ResolutionVoidType type, A argument) =>
-      visitType(type, argument);
+      visitInterfaceType(type, argument);
 
   @override
   R visitTypeVariableType(ResolutionTypeVariableType type, A argument) =>
@@ -1033,11 +1044,6 @@ abstract class AbstractTypeRelation
     throw 'internal error: unknown type kind ${t.kind}';
   }
 
-  bool visitVoidType(ResolutionVoidType t, ResolutionDartType s) {
-    assert(s is! ResolutionVoidType);
-    return false;
-  }
-
   bool invalidTypeArguments(ResolutionDartType t, ResolutionDartType s);
 
   bool invalidFunctionReturnTypes(ResolutionDartType t, ResolutionDartType s);
@@ -1743,7 +1749,7 @@ class Types implements DartTypes {
 
     if (a.treatAsDynamic || b.treatAsDynamic)
       return const ResolutionDynamicType();
-    if (a.isVoid || b.isVoid) return const ResolutionVoidType();
+    if (a.isVoid || b.isVoid) return new ResolutionVoidType(a.element);
 
     if (a.isFunctionType && b.isFunctionType) {
       return computeLeastUpperBoundFunctionTypes(a, b);