Fix onSelectorReturned unit tests

[antonok-edm]

Resolves brave/brave-browser#15109

Submitter Checklist:

• I confirm that no security/privacy review is needed, or that I have requested one
• There is a ticket for my issue
• Used Github auto-closing keywords in the PR description above
• Wrote a good PR/commit description
• Added appropriate labels (QA/Yes or QA/No; release-notes/include or release-notes/exclude; OS/...) to the associated issue
• Checked the PR locally: npm run test -- brave_browser_tests, npm run test -- brave_unit_tests, npm run lint, npm run gn_check, npm run tslint
• Ran git rebase master (if needed)

Reviewer Checklist:

• A security review is not needed, or a link to one is included in the PR description
• New files have MPL-2.0 license header
• Adequate test coverage exists to prevent regressions
• Major classes, functions and non-trivial code blocks are well-commented
• Changes in component dependencies are properly reflected in gn
• Code follows the style guide
• Test plan is specified in PR before merging

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on
• All relevant documentation has been updated, for instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-Compatibility-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

[bsclifton]

Looks like this has a few failures:

[2021-04-05T01:57:25.048Z] ERROR: /home/ubuntu/workspace/pr-brave-browser-fix-onSelectorReturned-unit-tests-pre-init/components/test/brave_extension/background/events/cosmeticFilterEvents_test.ts:89:13 - Promises must be handled appropriately

[2021-04-05T01:57:25.048Z] ERROR: /home/ubuntu/workspace/pr-brave-browser-fix-onSelectorReturned-unit-tests-pre-init/components/test/brave_extension/background/events/cosmeticFilterEvents_test.ts:96:13 - Promises must be handled appropriately

[2021-04-05T01:57:25.048Z] ERROR: /home/ubuntu/workspace/pr-brave-browser-fix-onSelectorReturned-unit-tests-pre-init/components/test/brave_extension/background/events/cosmeticFilterEvents_test.ts:111:11 - Promises must be handled appropriately

[2021-04-05T01:57:25.048Z] ERROR: /home/ubuntu/workspace/pr-brave-browser-fix-onSelectorReturned-unit-tests-pre-init/components/test/brave_extension/background/events/cosmeticFilterEvents_test.ts:120:11 - Promises must be handled appropriately

[2021-04-05T01:57:25.049Z] ERROR: /home/ubuntu/workspace/pr-brave-browser-fix-onSelectorReturned-unit-tests-pre-init/components/test/brave_extension/background/events/cosmeticFilterEvents_test.ts:125:11 - Promises must be handled appropriately

You should be able to run this locally from inside src/brave using npm run test-unit. Will take a look real quick

[bsclifton]

OK I think this just needed a rebase; original branch didn't have b80a029

CI re-running now 😄

[bsclifton]

++