Revert "The expected key is a valid identifier, which is already free of \\, <0x20, "."

test/mjsunit/json2.js

Index: test/mjsunit/json2.js
diff --git a/test/mjsunit/json2.js b/test/mjsunit/json2.js
index f048f05290c9bec50418ee37bb821bf5e8c8d3c4..f68c76c92ad563540f9ba8c7ec1e7ef468375fdd 100644
--- a/test/mjsunit/json2.js
+++ b/test/mjsunit/json2.js
@@ -183,3 +183,8 @@ try {
   externalizeString(str, true);
 } catch (e) { }
 TestStringify("\"external\"", str, null, 0);
+
+var o = {};
+o.somespecialproperty = 10;
+o["\x19"] = 10;
+assertThrows("JSON.parse('{\"somespecialproperty\":100, \"\x19\":10}')");