  
    /**
 diff --git a/src/com/google/javascript/rhino/jstype/JSType.java b/src/com/google/javascript/rhino/jstype/JSType.java
-index 9c8e9897..3f1360e3 100644
+index 9c8e9897..7906bfef 100644
 --- a/src/com/google/javascript/rhino/jstype/JSType.java
 +++ b/src/com/google/javascript/rhino/jstype/JSType.java
-@@ -488,17 +488,14 @@ public abstract class JSType implements Serializable {
+@@ -489,7 +489,7 @@ public abstract class JSType implements Serializable {
+    * Checks if two types are equivalent.
+    */
+   public final boolean isEquivalentTo(JSType that) {
+-    return checkEquivalenceHelper(that, EquivalenceMethod.IDENTITY);
++    return checkEquivalenceHelper(that, false);
+   }
+ 
    /**
-    * Checks if two types are equivalent.
-    */
--  public final boolean isEquivalentTo(JSType that) {
--    return checkEquivalenceHelper(that, EquivalenceMethod.IDENTITY);
-+  public final boolean isEquivalentTo(JSType jsType) {
-+    return checkEquivalenceHelper(jsType, false);
+@@ -497,7 +497,7 @@ public abstract class JSType implements Serializable {
+    * @see EquivalenceMethod
+    */
+   public final boolean isInvariant(JSType that) {
+-    return checkEquivalenceHelper(that, EquivalenceMethod.INVARIANT);
++    return checkEquivalenceHelper(that, false);
    }
  
    /**
-    * Checks if two types are invariant.
-    * @see EquivalenceMethod
-    */
--  public final boolean isInvariant(JSType that) {
--    return checkEquivalenceHelper(that, EquivalenceMethod.INVARIANT);
--  }
- 
-   /**
-    * Whether this type is meaningfully different from {@code that} type for
-@@ -511,25 +508,23 @@ public abstract class JSType implements Serializable {
+@@ -511,25 +511,23 @@ public abstract class JSType implements Serializable {
     *     unknowns</a>
     */
    public final boolean differsFrom(JSType that) {

       }
 
       JSType thisRootType = thisParamType == null ?
@@ -579,7 +574,7 @@ public abstract class JSType implements Serializable {
       JSType thatRootType = thatParamType == null ?
           that : thatParamType.getReferencedTypeInternal();
       return paramsMatch &&

         return false;
       }
     }
@@ -201,7 +201,8 @@ class RecordType extends PrototypeObjectType {
           JSType altPropType = alt.getPropertyType(propName);
           if (altPropType != null && !alt.isEquivalentTo(this) &&
