CSSTidy: preserve leading decimal zeros in Gutenberg

[ramonjd]

Fixes Automattic/wp-calypso#45629

Changes proposed in this Pull Request:

CSSTidy performs some "optimizations" that trigger Gutenberg block validation errors.

To prevent this, we've had to add some "optimizations" of our own to CSSTidy's inner workings. See, for example,
#19935

This PR adds a setting to CSSTidy to tell its optimizer to preserve leading decimal zeros.

Currently, CSSTidy strips the 0 from 0.7 resulting in .7.

For Gutenberg inline styles, 0.7 is a valid CSS value for line-height for example. Where the post body content contains .7, we see block validation errors 😱

TODO

• Add unit tests
• Fix linting issues 😸

Does this pull request change what data or activity we track or use?

Nope.

Testing instructions:

Patch your sandbox with the diff created by this PR

Create a paragraph or heading block and select a line-height value of less than 0

<!-- wp:paragraph {"style":{"typography":{"lineHeight":"0.4"}}} -->
<p style="line-height:0.4">AM I VALID? AM I?</p>
<!-- /wp:paragraph -->

Save the post and refresh the page.

You should not see any validation errors, e.g.,

Content generated by `save` function:

<p>AM I VALID? AM I?</p>

Content retrieved from post body:

<p style="line-height:.4;">AM I VALID? AM I?</p>

Unit tests

Run yarn docker:up from the Jetpack repo root directory.

In another terminal run yarn run docker:phpunit --testsuite csstidy.

[matticbot]

Caution: This PR has changes that must be merged to WordPress.com
Hello ramonjd! These changes need to be synced to WordPress.com - If you 're an a11n, please commandeer and confirm D62096-code works as expected before merging this PR. Once this PR is merged, please commit the changes to WP.com. Thank you!
This revision will be updated with each commit to this PR

[github-actions]

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Jetpack plugin:

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[glendaviesnz]

Tested well for me on sandbox. I couldn't get the unit tests to run locally, they gave a 'Cannot open file "csstidy.php".' error, but running on CI, so assume there is something broken in my local setup.

[github-actions]

Great news! One last step: head over to your WordPress.com diff, D62096-code, and commit it.
Once you've done so, come back to this PR and add a comment with your changeset ID.

Thank you!

[ramonjd]

r227276-wpcom