Support AdGuard set-constant value aliases 'emptyArr' and 'emptyObj'

[CuervoCarlos]

Prerequisites

• I verified that this is not a filter list issue. Report any issues with filter lists or broken website functionality in the uAssets issue tracker.
• This is not a support issue or a question. For support, questions, or help, visit /r/uBlockOrigin.
• I performed a cursory search of the issue tracker to avoid opening a duplicate issue.
• The issue is not present after disabling uBO in the browser.
• I checked the documentation to understand that the issue I am reporting is not normal behavior.

I tried to reproduce the issue when...

• uBO is the only extension.
• uBO uses default lists and settings.
• using a new, unmodified browser profile.

Description

AdGuard scriptlets implement different literal value using 'emptyArr' and 'emptyObj' instead of '[]' and '{}' in uBO. Please consider implementing those aliases since uBO is the only out-of-the-box privacy filter featuring scriptlets (and the other being EasyPrivacy which does not manipulate Javascript).

References:
AdG set-constant
uBO set-constant

A specific URL where the issue occurs.

mirrormedia.mg

Steps to Reproduce

Rule *##+js(set, window.test, emptyArr) is not resolved.
Rule *##+js(set, window.test, emptyObj) is not resolved.

Expected behavior

Example AdG grammar:
mirrormedia.mg##+js(set-constant, dataLayer, emptyArr)

should work the same as uBO grammar:
mirrormedia.mg##+js(set-constant, dataLayer, [])

Actual behavior

Rule mirrormedia.mg##+js(set-constant, dataLayer, emptyArr) is not resolved; nothing happens in the logger.

uBO version

1.45.2

Browser name and version

Firefox 102.0

Operating System and version

Windows 10

[gorhill]

The filter in original "AdGuard Tracking Protection" list is:

mirrormedia.mg#%#//scriptlet("set-constant", "dataLayer", "emptyArr")

This means it's improperly converted to uBO's syntax. The conversion should be fixed in AdGuard's converter, it's already done for empty string (ref).

[superlex]

@gorhill
I assume the same goes for set-local-storage-item / set-session-storage-item .

This is the result of

example.org#%#//scriptlet('set-local-storage-item', 'ag_obj', 'emptyObj')
example.org#%#//scriptlet('set-local-storage-item', 'ag_arr', 'emptyArr')
example.org#%#//scriptlet('set-local-storage-item', 'ag_str', '')
example.org##+js(set-local-storage-item, u_obj, {})
example.org##+js(set-local-storage-item, u_arr, [])
example.org##+js(set-local-storage-item, u_str, '')

References:
https://github.com/gorhill/uBlock/wiki/Resources-Library#set-local-storage-itemjs-
https://github.com/AdguardTeam/Scriptlets/blob/master/wiki/about-scriptlets.md#set-local-storage-item
https://github.com/AdguardTeam/Scriptlets/blob/master/wiki/about-scriptlets.md#set-session-storage-item

PS:
Let me know if you prefer I open a new issue and/or you need additional information.