Only walk the hidden prototype chain for private nonexistent symbols

test/mjsunit/regress/regress-479528.js

Index: test/mjsunit/regress/regress-479528.js
diff --git a/test/mjsunit/compiler/regress-491578.js b/test/mjsunit/regress/regress-479528.js
similarity index 57%
copy from test/mjsunit/compiler/regress-491578.js
copy to test/mjsunit/regress/regress-479528.js
index c27570456c31e9a191fe1f4f1ea17b80f29de98e..be0dfaff45babd4e88fcf91ab0931fbfc3a59afe 100644
--- a/test/mjsunit/compiler/regress-491578.js
+++ b/test/mjsunit/regress/regress-479528.js
@@ -4,12 +4,10 @@
 
 // Flags: --allow-natives-syntax
 
-function foo(x) {
-  if (x === undefined) return;
-  while (true) {
-    while (1 || 2) { }
-    f();
-  }
+var __v_7 = {"__proto__": this};
+__v_9 = %CreatePrivateSymbol("__v_9");
+this[__v_9] = "moo";
+function __f_5() {
+    __v_7[__v_9] = "bow-wow";
 }
-%OptimizeFunctionOnNextCall(foo);
-foo();
+__f_5();