diff --git a/dev/core/src/com/google/gwt/dev/jjs/ast/JArrayType.java b/dev/core/src/com/google/gwt/dev/jjs/ast/JArrayType.java
index d05cdc4d97e..df5ebad516d 100644
--- a/dev/core/src/com/google/gwt/dev/jjs/ast/JArrayType.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/ast/JArrayType.java
@@ -58,6 +58,11 @@ public String getJsniSignatureName() {
     return "[" + elementType.getJsniSignatureName();
   }
 
+  @Override
+  public JEnumType isEnumOrSubclass() {
+    return null;
+  }
+
   public JType getLeafType() {
     if (leafType == null) {
       if (elementType instanceof JArrayType) {
@@ -94,6 +99,16 @@ public boolean canBeImplementedExternally() {
     return getLeafType().canBeImplementedExternally();
   }
 
+  @Override
+  public boolean isJsType() {
+    return false;
+  }
+
+  @Override
+  public boolean isJsFunction() {
+    return false;
+  }
+
   @Override
   public boolean isJsNative() {
     return getLeafType().isJsNative();
@@ -110,6 +125,11 @@ public boolean canBeReferencedExternally() {
         && !getLeafType().isJavaLangObject();
   }
 
+  @Override
+  public boolean isJavaLangObject() {
+    return false;
+  }
+
   @Override
   public boolean replaces(JType originalType) {
     return (originalType instanceof JArrayType)
diff --git a/dev/core/src/com/google/gwt/dev/jjs/ast/JDeclaredType.java b/dev/core/src/com/google/gwt/dev/jjs/ast/JDeclaredType.java
index 29d8d158edb..56d77c59414 100755
--- a/dev/core/src/com/google/gwt/dev/jjs/ast/JDeclaredType.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/ast/JDeclaredType.java
@@ -365,6 +365,11 @@ public Iterable<JMember> getMembers() {
     return Iterables.<JMember>concat(fields, methods);
   }
 
+  @Override
+  public boolean isArrayType() {
+    return false;
+  }
+
   @Override
   public boolean isJsType() {
     return isJsType;
diff --git a/dev/core/src/com/google/gwt/dev/jjs/ast/JInterfaceType.java b/dev/core/src/com/google/gwt/dev/jjs/ast/JInterfaceType.java
index 01f1c275c3d..be8f9c39a7a 100644
--- a/dev/core/src/com/google/gwt/dev/jjs/ast/JInterfaceType.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/ast/JInterfaceType.java
@@ -76,6 +76,16 @@ public boolean isJsoType() {
     return false;
   }
 
+  @Override
+  public boolean isJavaLangObject() {
+    return false;
+  }
+
+  @Override
+  public JEnumType isEnumOrSubclass() {
+    return null;
+  }
+
   public boolean hasDefaultMethods() {
     assert !isExternal();
     return Iterables.any(getMethods(), new Predicate<JMethod>() {
diff --git a/dev/core/src/com/google/gwt/dev/jjs/ast/JPrimitiveType.java b/dev/core/src/com/google/gwt/dev/jjs/ast/JPrimitiveType.java
index 9bcabb5950b..c13dae2bb59 100644
--- a/dev/core/src/com/google/gwt/dev/jjs/ast/JPrimitiveType.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/ast/JPrimitiveType.java
@@ -74,6 +74,31 @@ public boolean canBeNull() {
     return false;
   }
 
+  @Override
+  public boolean isArrayType() {
+    return false;
+  }
+
+  @Override
+  public boolean isJsType() {
+    return false;
+  }
+
+  @Override
+  public boolean isJsFunction() {
+    return false;
+  }
+
+  @Override
+  public boolean isJsNative() {
+    return false;
+  }
+
+  @Override
+  public boolean canBeImplementedExternally() {
+    return false;
+  }
+
   @Override
   public boolean canBeSubclass() {
     return false;
@@ -98,6 +123,11 @@ public String getJsniSignatureName() {
     return signatureName;
   }
 
+  @Override
+  public JEnumType isEnumOrSubclass() {
+    return null;
+  }
+
   public String getWrapperTypeName() {
     return wrapperTypeName;
   }
@@ -117,6 +147,11 @@ public boolean canBeReferencedExternally() {
     return this != JPrimitiveType.LONG;
   }
 
+  @Override
+  public boolean isJavaLangObject() {
+    return false;
+  }
+
   @Override
   public void traverse(JVisitor visitor, Context ctx) {
     if (visitor.visit(this, ctx)) {
diff --git a/dev/core/src/com/google/gwt/dev/jjs/ast/JReferenceType.java b/dev/core/src/com/google/gwt/dev/jjs/ast/JReferenceType.java
index 91075689cd9..8398ab320b3 100644
--- a/dev/core/src/com/google/gwt/dev/jjs/ast/JReferenceType.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/ast/JReferenceType.java
@@ -40,6 +40,11 @@ public String getJsniSignatureName() {
           return "N";
         }
 
+        @Override
+        public JEnumType isEnumOrSubclass() {
+          return null;
+        }
+
         @Override
         public boolean isAbstract() {
           return false;
@@ -55,11 +60,46 @@ public boolean isJsoType() {
           return false;
         }
 
+        @Override
+        public boolean isArrayType() {
+          return false;
+        }
+
         @Override
         public boolean isNullType() {
           return true;
         }
 
+        @Override
+        public boolean isJsType() {
+          return false;
+        }
+
+        @Override
+        public boolean isJsFunction() {
+          return false;
+        }
+
+        @Override
+        public boolean isJsNative() {
+          return false;
+        }
+
+        @Override
+        public boolean canBeImplementedExternally() {
+          return false;
+        }
+
+        @Override
+        public boolean canBeReferencedExternally() {
+          return false;
+        }
+
+        @Override
+        public boolean isJavaLangObject() {
+          return false;
+        }
+
         @Override
         public void traverse(JVisitor visitor, Context ctx) {
           if (visitor.visit(this, ctx)) {
@@ -145,11 +185,41 @@ public boolean isArrayType() {
       return ref.isArrayType();
     }
 
+    @Override
+    public boolean isJsType() {
+      return ref.isJsType();
+    }
+
+    @Override
+    public boolean isJsFunction() {
+      return ref.isJsFunction();
+    }
+
     @Override
     public boolean isJsoType() {
       return ref.isJsoType();
     }
 
+    @Override
+    public boolean isJsNative() {
+      return ref.isJsNative();
+    }
+
+    @Override
+    public boolean canBeImplementedExternally() {
+      return ref.canBeImplementedExternally();
+    }
+
+    @Override
+    public boolean canBeReferencedExternally() {
+      return ref.canBeReferencedExternally();
+    }
+
+    @Override
+    public boolean isJavaLangObject() {
+      return ref.isJavaLangObject();
+    }
+
     @Override
     public boolean isExternal() {
       return ref.isExternal();
diff --git a/dev/core/src/com/google/gwt/dev/jjs/ast/JType.java b/dev/core/src/com/google/gwt/dev/jjs/ast/JType.java
index 82a40f51b46..a645b8bd4dd 100644
--- a/dev/core/src/com/google/gwt/dev/jjs/ast/JType.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/ast/JType.java
@@ -62,9 +62,7 @@ public JType(SourceInfo info, String name) {
    */
   public abstract boolean canBeNull();
 
-  public boolean isArrayType() {
-    return false;
-  }
+  public abstract boolean isArrayType();
 
   /**
    * Returns {@code true} if this is {@link JReferenceType.JNullType.INSTANCE}.
@@ -73,29 +71,17 @@ public boolean isNullType() {
     return false;
   }
 
-  public boolean isJsType() {
-    return false;
-  }
+  public abstract boolean isJsType();
 
-  public boolean isJsFunction() {
-    return false;
-  }
+  public abstract boolean isJsFunction();
 
-  public boolean isJsNative() {
-    return false;
-  }
+  public abstract boolean isJsNative();
 
-  public boolean canBeImplementedExternally() {
-    return false;
-  }
+  public abstract boolean canBeImplementedExternally();
 
-  public boolean canBeReferencedExternally() {
-    return false;
-  }
+  public abstract boolean canBeReferencedExternally();
 
-  public boolean isJavaLangObject() {
-    return false;
-  }
+  public abstract boolean isJavaLangObject();
 
   /**
    * Returns {@code true} if this is a JavaScriptObject type.
@@ -161,9 +147,7 @@ public String getPackageName() {
    * Returns the (closest) enum supertype if the type is a subclass of an enum; it returns
    * {@code this} if {@code this} is a {@link JEnumType} and {@code null} otherwise.
    */
-  public JEnumType isEnumOrSubclass() {
-    return null;
-  }
+  public abstract JEnumType isEnumOrSubclass();
 
   /**
    * Binary name of the type.