Gabriel Ivăncescu (@insn) commented about dlls/jscript/array.c:
} add_args = argc-2;
- } else if (argc && ctx->html_mode) {
delete_cnt = length-start;
Are you sure this is html mode specific? To confirm, you should move the test to `documentmode.js` and see what happens in every mode, `es5.js` is for ES5+ (IE9+, but we test it in IE11 mode only).
If it turns out to be ES5 for example, you can use ctx->version >= SCRIPTLANGUAGEVERSION_ES5 instead. Otherwise you can keep html mode of course, if it works in all modes the same.