browser-engine-gecko-*: Explicitly set autofill flag.

[pocmo]

Fixes mozilla-mobile/fenix#617

Pull Request checklist

• Quality: This PR builds and passes detekt/ktlint checks (A pre-push hook is recommended)
• Tests: This PR includes thorough tests or an explanation of why it does not
• Changelog: This PR includes a changelog entry or does not need one
• Accessibility: The code in this PR follows accessibility best practices or does not include any user facing features

[codecov]

Codecov Report

Merging #2149 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #2149      +/-   ##
============================================
- Coverage     84.88%   84.87%   -0.01%     
+ Complexity     2357     2350       -7     
============================================
  Files           279      279              
  Lines          9627     9621       -6     
  Branches       1418     1418              
============================================
- Hits           8172     8166       -6     
  Misses          872      872              
  Partials        583      583

Impacted Files	Coverage Δ	Complexity Δ
...illa/components/service/glean/BooleanMetricType.kt	93.33% <0%> (-1.91%)	10% <0%> (-7%)

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[codecov]

Codecov Report

Merging #2149 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #2149      +/-   ##
============================================
- Coverage     84.88%   84.87%   -0.01%     
+ Complexity     2357     2350       -7     
============================================
  Files           279      279              
  Lines          9627     9621       -6     
  Branches       1418     1418              
============================================
- Hits           8172     8166       -6     
  Misses          872      872              
  Partials        583      583

Impacted Files	Coverage Δ	Complexity Δ
...illa/components/service/glean/BooleanMetricType.kt	93.33% <0%> (-1.91%)	10% <0%> (-7%)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 7fb2660...e6a6f5b. Read the comment docs.

[Amejia481]

👍