executeInstanceExec() and executeClassExec() are only used with a block

Author: eregon

src/main/java/org/truffleruby/core/basicobject/BasicObjectNodes.java

@@ -394,7 +394,7 @@ public static InstanceExecNode create() {
 
         @Child private CallBlockNode callBlockNode = CallBlockNode.create();
 
-        public abstract Object executeInstanceExec(Object self, Object[] args, Object block);
+        abstract Object executeInstanceExec(Object self, Object[] args, DynamicObject block);
 
         @Specialization
         protected Object instanceExec(Object receiver, Object[] arguments, DynamicObject block) {

src/main/java/org/truffleruby/core/module/ModuleNodes.java

@@ -760,7 +760,7 @@ public static ClassExecNode create() {
 
         @Child private CallBlockNode callBlockNode = CallBlockNode.create();
 
-        public abstract Object executeClassExec(DynamicObject self, Object[] args, Object block);
+        abstract Object executeClassExec(DynamicObject self, Object[] args, DynamicObject block);
 
         @Specialization
         protected Object classExec(DynamicObject self, Object[] args, DynamicObject block) {