Fix firestore wrong variables issue

[EvilMouth]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines.
• Tests for the changes have been added (for bug fixes / features).
  • Muse | Mist have been tested.
  • Pisces | Gemini have been tested.
• Docs have been added / updated (for bug fixes / features).

PR Type

What kind of change does this PR introduce?

• Bugfix.
• Feature.
• Code style update (formatting, local variables).
• Refactoring (no functional changes, no api changes).
• Build related changes.
• CI related changes.
• Documentation content changes.
• Other... Please describe:

What is the current behavior?

#387
Issue Number(s): #387

What is the new behavior?

Description about this pull, in several words...
Fixed firestore use wrong variables problem

• Screens with this changes: EvilMouth@62aa127
• Link to demo site with this changes: EvilMouth@62aa127

How to use?

In NexT _config.yml:

firestore:
  enable: true

Does this PR introduce a breaking change?

• Yes.
• No.

[maple3142]

Besides, I haven't used this plugin for a while because of the size of the external js files.(firebase & firestore)
As a result, what about deprecate this plugin? @ivan-nginx

[ivan-nginx]

FireStore – Google tool.
LeanCloud – China tool.

I think no need deprecate geolocation tools because theme must be for all peoples in the world.