[intl] Avoid modifying options bag from constructor

test/mjsunit/regress/regress-builtinbust-7.js

Index: test/mjsunit/regress/regress-builtinbust-7.js
diff --git a/test/mjsunit/regress/regress-builtinbust-7.js b/test/mjsunit/regress/regress-builtinbust-7.js
index a7c049e9086088f0825d06114a4557fce4efbb64..8581eead7fca39073d9d056e5b3cbf62997950ea 100644
--- a/test/mjsunit/regress/regress-builtinbust-7.js
+++ b/test/mjsunit/regress/regress-builtinbust-7.js
@@ -24,7 +24,7 @@ if ("Intl" in this) {
   assertDoesNotThrow(function() {
     date.toLocaleDateString("de-DE", options_incomplete);
   });
-  assertTrue(options_incomplete.hasOwnProperty("year"));
+  assertFalse(options_incomplete.hasOwnProperty("year"));
 
   assertDoesNotThrow(function() { date.toLocaleDateString("de-DE", undefined); });
   assertDoesNotThrow(function() { date.toLocaleDateString("de-DE"); });