fix(mock-doc): add missing methods to the element mock

[erwinheitzman]

NOTE: I have previously created issues and example repositories but since this is a really small PR that does not impact any users directly, I feel that this can be done without an accompanied issue. If you feel differently about this, do say so.

Add missing methods to the mock-doc MockElement class.

Pull request checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• Build (npm run build) was run locally and any changes were pushed
• Unit tests (npm test) were run locally and passed
• E2E Tests (npm run test.karma.prod) were run locally and passed
• Prettier (npm run prettier) was run locally and passed

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

The methods that have been added were missing, causing errors.

GitHub Issue Number: N/A

What is the new behavior?

No error is thrown when your component uses any of the methods while running unit tests.

Does this introduce a breaking change?

• Yes
• No

[rwaskiewicz]

LGTM, thanks!

[rwaskiewicz]

For historical purposes: I'm going to merge this as an admin. The "Tech Debt Burndown / Download error files and report (pull_request)" currently fails on PRs that come from forks. It generates the report just fine (which for this PR, states we are not introducing any unused functions / strictNullChecks violations), but can't add the comment to the PR with the report's contents. We'll fix this next sprint, but I don't see that as a reason to block the PR in the meantime

[rwaskiewicz]

The fix for this issue has been officially released as a part of Stencil v2.17.2.