Can now specify parent class in extend() when implementing atop an empty base

lib/class.js

@@ -113,7 +113,7 @@ module.exports.implement = function()
 {
     // implement on empty base
     return createImplement(
-        module.exports.extend(),
+        null,
         Array.prototype.slice.call( arguments )
     );
 };

test/test-class-implement.js

@@ -213,3 +213,22 @@ var Type = Interface.extend( {
     );
 } )();
 
+
+/**
+ * Opposite of the above test. If a parent wasn't specified to begin with, then
+ * we're fine to specify it in extend().
+ */
+( function testCanSpecifyParentIfImplementingAtopEmptyClass()
+{
+    assert.doesNotThrow(
+        function()
+        {
+            // this /should/ work
+            Class.implement( Type ).extend( PlainFoo, {} );
+        },
+        Error,
+        "Can specify parent for exetnd() when implementing atop an " +
+            "empty base"
+    );
+} )();
+