Simplify toString() for dispatch nodes

Author: eregon

src/main/java/org/truffleruby/language/dispatch/CachedBoxedDispatchNode.java

@@ -108,9 +108,9 @@ public Object executeDispatch(
     public String toString() {
         return StringUtils.format(
                 "CachedBoxedDispatchNode(:%s, %x, %s)",
-                getCachedName().toString(),
+                getCachedName(),
                 expectedShape.hashCode(),
-                method == null ? "null" : method.toString());
+                method);
     }
 
 }

src/main/java/org/truffleruby/language/dispatch/CachedSingletonDispatchNode.java

@@ -106,11 +106,11 @@ public Object executeDispatch(
     @Override
     public String toString() {
         return StringUtils.format(
-                "CachedBoxedDispatchNode(:%s, %s@%x, %s)",
-                getCachedName().toString(),
+                "CachedSingletonDispatchNode(:%s, %s@%x, %s)",
+                getCachedName(),
                 expectedReceiver,
                 expectedReceiver.hashCode(),
-                method == null ? "null" : method.toString());
+                method);
     }
 
 }