[regexp] Remove unused code

test/mjsunit/es6/classes-subclass-builtins.js

Index: test/mjsunit/es6/classes-subclass-builtins.js
diff --git a/test/mjsunit/es6/classes-subclass-builtins.js b/test/mjsunit/es6/classes-subclass-builtins.js
index dca514c294e8b4965c7f078a03faccc951e05ab0..23cb6c06df8f8e9ffbafe0c2d28a5c5ed859dae4 100644
--- a/test/mjsunit/es6/classes-subclass-builtins.js
+++ b/test/mjsunit/es6/classes-subclass-builtins.js
@@ -920,7 +920,6 @@ function TestMapSetSubclassing(container, is_map) {
   assertEquals(["match", "tostring"], log);
   // TODO(littledan): Is the RegExp constructor correct to create
   // the internal slots and do these type checks this way?
-  assertEquals("biep", %_RegExpSource(o));
   assertThrows(() => Object.getOwnPropertyDescriptor(RegExp.prototype,
                                                      'source').get(o),
                TypeError);