fix: stack overflow!!

runtime/src/main/java/me/topchetoeu/j2s/runtime/values/primitives/StringValue.java

@@ -57,7 +57,7 @@ public final class StringValue implements PrimitiveValue {
 			}
 		}
 
-		return StringValue.this.getOwnMember(env, key);
+		return PrimitiveValue.super.getOwnMember(env, key);
 	}
 
 	@Override public Set<String> getOwnMembers(Environment env, boolean onlyEnumerable) {