Quick check for self in InterfaceTypeImpl.getLeastUpperBound()

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

Index: editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/type/InterfaceTypeImpl.java
diff --git a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/type/InterfaceTypeImpl.java b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/type/InterfaceTypeImpl.java
index 0a20ef81f2028b0f7c74f47a460f076f87fa2f1f..4242f7671e7074460228fda63af599b7a8b9a250 100644
--- a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/type/InterfaceTypeImpl.java
+++ b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/type/InterfaceTypeImpl.java
@@ -285,6 +285,11 @@ public class InterfaceTypeImpl extends TypeImpl implements InterfaceType {
 
   @Override
   public Type getLeastUpperBound(Type type) {
+    // quick check for self
+    if (type == this) {
+      return this;
+    }
+    // dynamic
     Type dynamicType = DynamicTypeImpl.getInstance();
     if (this == dynamicType || type == dynamicType) {
       return dynamicType;