Fix stray space

[yucheng11122017]

What is the purpose of this pull request?

• [ ] Documentation update
• [x] Bug fix
• [ ] Feature addition or enhancement
• [ ] Code maintenance
• [ ] DevOps
• [ ] Improve developer experience
• [ ] Others, please explain:

Overview of changes: Resolve #2419, modified vue(modification made at minimal scope via trial and error) and add test; Credit to @kaixin-hc for investigating the cause of the bug.

Anything you'd like to highlight/discuss:

Testing instructions: Test with markbind serve -d

Proposed commit message: (wrap lines at 72 characters) Fix stray space before popover and tooltip

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Checklist: :ballot_box_with_check:

• [ ] Updated the documentation for feature additions and enhancements
• [x] Added tests for bug fixes or features
• [x] Linked all related issues
• [x] No unrelated changes

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Reviewer checklist:

Indicate the SEMVER impact of the PR:

• [ ] Major (when you make incompatible API changes)
• [ ] Minor (when you add functionality in a backward compatible manner)
• [x] Patch (when you make backward compatible bug fixes)

At the end of the review, please label the PR with the appropriate label: r.Major, r.Minor, r.Patch.

Breaking change release note preparation (if applicable):

• To be included in the release note for any feature that is made obsolete/breaking

Give a brief explanation note about:

• what was the old feature that was made obsolete
• any replacement feature (if any), and
• how the author should modify his website to migrate from the old feature to the replacement feature (if possible).

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 51.50%. Comparing base (cab80b7) to head (cbe3ede). Report is 6 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2499 +/- ## ========================================== + Coverage 51.11% 51.50% +0.38% ========================================== Files 124 124 Lines 5355 5398 +43 Branches 1152 1152 ========================================== + Hits 2737 2780 +43 Misses 2328 2328 Partials 290 290 ```

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