Fix for 11987.

editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/type/VoidTypeImpl.java

Index: editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/type/VoidTypeImpl.java
diff --git a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/type/VoidTypeImpl.java b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/type/VoidTypeImpl.java
index 3589b278b85703088aeeaa03d231fe8bdd49b25d..a238cecf3bdb81ddc998e6faadabc40445bd5ef4 100644
--- a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/type/VoidTypeImpl.java
+++ b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/type/VoidTypeImpl.java
@@ -17,6 +17,8 @@ import com.google.dart.engine.scanner.Keyword;
 import com.google.dart.engine.type.Type;
 import com.google.dart.engine.type.VoidType;
 
+import java.util.Set;
+
 /**
  * The unique instance of the class {@code VoidTypeImpl} implements the type {@code void}.
  * 
@@ -50,26 +52,27 @@ public class VoidTypeImpl extends TypeImpl implements VoidType {
   }
 
   @Override
-  public boolean isMoreSpecificThan(Type type, boolean withDynamic) {
-    return isSubtypeOf(type);
+  public boolean isVoid() {
+    return true;
   }
 
   @Override
-  public boolean isSubtypeOf(Type type) {
-    // The only subtype relations that pertain to void are therefore:
-    // void <: void (by reflexivity)
-    // bottom <: void (as bottom is a subtype of all types).
-    // void <: dynamic (as dynamic is a supertype of all types)
-    return type == this || type == DynamicTypeImpl.getInstance();
+  public VoidTypeImpl substitute(Type[] argumentTypes, Type[] parameterTypes) {
+    return this;
   }
 
   @Override
-  public boolean isVoid() {
-    return true;
+  protected boolean internalIsMoreSpecificThan(Type type, boolean withDynamic,
+      Set<TypePair> visitedTypePairs) {
+    return isSubtypeOf(type);
   }
 
   @Override
-  public VoidTypeImpl substitute(Type[] argumentTypes, Type[] parameterTypes) {
-    return this;
+  protected boolean internalIsSubtypeOf(Type type, Set<TypePair> visitedTypePairs) {
+    // The only subtype relations that pertain to void are therefore:
+    // void <: void (by reflexivity)
+    // bottom <: void (as bottom is a subtype of all types).
+    // void <: dynamic (as dynamic is a supertype of all types)
+    return type == this || type == DynamicTypeImpl.getInstance();
   }
 }