Forms: allow height control for textarea

[simison]

Resolves FORMS-451

Proposed changes:

• Adds new textarea block with height control to adjust its height

Screen.Recording.2025-12-09.at.15.15.04.mov

Other information:

• Have you written new tests for your changes, if applicable?
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Testing instructions:

• Go to '..'

[github-actions]

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bin/jetpack-downloader test jetpack update/forms-text-field-height

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[github-actions]

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Jetpack plugin:

The Jetpack plugin has different release cadences depending on the platform:

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  • Scheduled release: January 6, 2026

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[jp-launch-control]

Code Coverage Summary

Coverage changed in 1 file.

File	Coverage	Δ%	Δ Uncovered
projects/packages/forms/src/blocks/contact-form/class-contact-form-block.php	524/628 (83.44%)	1.01%	0 💚

3 files are newly checked for coverage.

File	Coverage
projects/packages/forms/src/blocks/textarea/edit.js	0/21 (0.00%) 💔
projects/packages/forms/src/blocks/textarea/index.js	0/2 (0.00%) 💔
projects/packages/forms/src/blocks/textarea/save.js	0/1 (0.00%) 💔

Full summary · PHP report · JS report

_{If appropriate, add one of these labels to override the failing coverage check: Covered by non-unit tests Use to ignore the Code coverage requirement check when E2Es or other non-unit tests cover the code Coverage tests to be added later Use to ignore the Code coverage requirement check when tests will be added in a follow-up PR I don't care about code coverage for this PR Use this label to ignore the check for insufficient code coveage.}

[github-actions]

This PR has been marked as stale. This happened because:

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If this PR is still useful, please do a [trunk merge or rebase](https://github.com/Automattic/jetpack/blob/trunk/docs/git-workflow.md#keeping-your-branch-up-to-date) and otherwise make sure it's up to date and has clear testing instructions. You may also want to ping possible reviewers in case they've forgotten about it. Please close this PR if you think it's not valid anymore — if you do, please add a brief explanation.

If the PR is not updated (or at least commented on) in another month, it will be automatically closed.