[es6] Fix prototype chain walk for instanceof.

test/mjsunit/regress/regress-5085.js

Index: test/mjsunit/regress/regress-5085.js
diff --git a/test/mjsunit/regress/regress-crbug-476477-2.js b/test/mjsunit/regress/regress-5085.js
similarity index 69%
copy from test/mjsunit/regress/regress-crbug-476477-2.js
copy to test/mjsunit/regress/regress-5085.js
index 4dbb41b7d4ced16b488f6e1d00f184446bd41368..0ed034dc2d09e97827e2b4881570d60be2b5072b 100644
--- a/test/mjsunit/regress/regress-crbug-476477-2.js
+++ b/test/mjsunit/regress/regress-5085.js
@@ -5,12 +5,10 @@
 // Flags: --allow-natives-syntax
 
 function foo(x) {
-  var s = Math.floor(x / 3600);
-  Math.floor(s);
-  return s % 24;
+  return x instanceof Proxy;
 }
 
-foo(12345678);
-foo(12345678);
+assertFalse(foo({}));
+assertFalse(foo({}));
 %OptimizeFunctionOnNextCall(foo);
-foo(12345678);
+assertFalse(foo({}));