Add type presentation for function types.

sdk/lib/_internal/compiler/implementation/dart_types.dart

Index: sdk/lib/_internal/compiler/implementation/dart_types.dart
diff --git a/sdk/lib/_internal/compiler/implementation/dart_types.dart b/sdk/lib/_internal/compiler/implementation/dart_types.dart
index ec79917d6858c80dbf36c8320d8d9f55d2e20c33..81539d2400b0df14ec9c0b1390c10c684981df32 100644
--- a/sdk/lib/_internal/compiler/implementation/dart_types.dart
+++ b/sdk/lib/_internal/compiler/implementation/dart_types.dart
@@ -102,6 +102,16 @@ abstract class DartType {
 
   DartType asRaw() => this;
 
+  /**
+   * Is [: true :] if this type is the dynamic type.
+   */
+  bool get isDynamic => false;
+
+  /**
+   * Is [: true :] if this type is the void type.
+   */
+  bool get isVoid => false;
+
   accept(DartTypeVisitor visitor, var argument);
 }
 
@@ -239,6 +249,8 @@ class VoidType extends DartType {
     return visitor.visitVoidType(this, argument);
   }
 
+  bool get isVoid => true;
+
   int get hashCode => 1729;
 
   bool operator ==(other) => other is VoidType;
@@ -737,6 +749,8 @@ class DynamicType extends InterfaceType {
 
   SourceString get name => const SourceString('dynamic');
 
+  bool get isDynamic => true;
+
   accept(DartTypeVisitor visitor, var argument) {
     return visitor.visitDynamicType(this, argument);
   }