fix(whiskers): use block context in darklight helper

[backwardspy]

template:

{{#each flavors}}
{{flavorName}} {{isLight}} {{darklight "night" "day"}}
{{/each}}

output before fix:

Latte true night
Frappé false night
Macchiato false night
Mocha false night

output after fix:

Latte true day
Frappé false night
Macchiato false night
Mocha false night

[sgoudham]

As mentioned via VC, this is a workaround that gets the job done.

I'd imagine we'll want to rethink the architecture of whiskers and/or potentially move to a different rendering engine to try and fit our usecase(s) better.

Thanks!