fix: correctly handle method invocations on getters

[incendial]

What is the purpose of this pull request? (put an "X" next to an item)

[ ] Documentation update
[X] Bug fix
[ ] New rule
[ ] Changes an existing rule
[ ] Add autofixing to a rule
[ ] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:

[github-actions]

Dart Code Metrics unused files report of dart_code_metrics. ✅

Summary

• Scanned package folders: bin, example, lib
• No unused files found! ✅

[github-actions]

Dart Code Metrics analyze report of dart_code_metrics. ✅

Summary

• Scanned folders: bin, example, lib, test

• Total scanned files: 357

• Total lines of source code: 6380

• Total classes: 240

• Average Cyclomatic Number per line of code: 0.35 / 1

• Average Source Lines of Code per method: 6

• Total tech debt: 1034.0 hours

• Found issues: 6 ⚠

[codecov]

Codecov Report

Merging #642 (288d249) into master (c6d909a) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #642      +/-   ##
==========================================
+ Coverage   86.10%   86.11%   +0.01%     
==========================================
  Files         235      235              
  Lines        5037     5043       +6     
==========================================
+ Hits         4337     4343       +6     
  Misses        700      700              

Impacted Files	Coverage Δ
...zers/unused_l10n_analyzer/unused_l10n_visitor.dart	98.76% <100.00%> (+0.09%)	⬆️

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