Fix for 11987.

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

Index: editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/type/BottomTypeImpl.java
diff --git a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/type/BottomTypeImpl.java b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/type/BottomTypeImpl.java
index e7144bfb877c23d47767c14da70e32c796b06ea5..a75e99256f48fe972e4f6ec06c138099f5de93f0 100644
--- a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/type/BottomTypeImpl.java
+++ b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/type/BottomTypeImpl.java
@@ -15,6 +15,8 @@ package com.google.dart.engine.internal.type;
 
 import com.google.dart.engine.type.Type;
 
+import java.util.Set;
+
 /**
  * The unique instance of the class {@code BottomTypeImpl} implements the type {@code bottom}.
  * 
@@ -53,24 +55,25 @@ public class BottomTypeImpl extends TypeImpl {
   }
 
   @Override
-  public boolean isMoreSpecificThan(Type type, boolean withDynamic) {
-    return true;
+  public boolean isSupertypeOf(Type type) {
+    // bottom is a subtype of all types
+    return false;
   }
 
   @Override
-  public boolean isSubtypeOf(Type type) {
-    // bottom is a subtype of all types
-    return true;
+  public BottomTypeImpl substitute(Type[] argumentTypes, Type[] parameterTypes) {
+    return this;
   }
 
   @Override
-  public boolean isSupertypeOf(Type type) {
-    // bottom is a subtype of all types
-    return false;
+  protected boolean internalIsMoreSpecificThan(Type type, boolean withDynamic,
+      Set<TypePair> visitedTypePairs) {
+    return true;
   }
 
   @Override
-  public BottomTypeImpl substitute(Type[] argumentTypes, Type[] parameterTypes) {
-    return this;
+  protected boolean internalIsSubtypeOf(Type type, Set<TypePair> visitedTypePairs) {
+    // bottom is a subtype of all types
+    return true;
   }
 }