Add AMP support for shortcodes and oEmbeds for Crowdsignal (Polldaddy)

[westonruter]

This consolidates the logic for rendering AMP versions of Crowdsignal/Polldaddy polls and surveys from the AMP plugin. See ampproject/amp-wp#1929 for the code that this PR makes obsolete in the AMP plugin.

This PR also makes sure that a title shortcode attribute gets passed onto the rendered poll link on the frontend.

I assume this code would also need to be copied into the Crowdsignal plugin.

See #9730.

Changes proposed in this Pull Request:

• Add first-party AMP compatibility for polls and surveys that are rendered via oEmbeds/shortcodes for Crowdsignal/Polldaddy. Note that the AMP versions of these are just links back to take the poll/survey.

Testing instructions:

To test:

1. Create a post with the below post_content.
2. Install the AMP plugin from source.
3. Check out the remove/bundled-polldaddy branch of the AMP plugin (see Add first-party support for Crowdsignal poll/survey oEmbeds ampproject/amp-wp#1929)
4. Compare the non-AMP with the AMP version of the post. There should be no AMP validation errors reported by the plugin and each of the polls/surveys should have some representation in the content.

Given this post_content:

<!-- wp:heading -->
<h2>Poll</h2>
<!-- /wp:heading -->

<!-- wp:core-embed/crowdsignal {"url":"https://polldaddy.com/poll/7012505/","type":"rich","providerNameSlug":"crowdsignal","className":""} -->
<figure class="wp-block-embed-crowdsignal wp-block-embed is-type-rich is-provider-crowdsignal"><div class="wp-block-embed__wrapper">
https://polldaddy.com/poll/7012505/
</div><figcaption>Poll oEmbed</figcaption></figure>
<!-- /wp:core-embed/crowdsignal -->

<!-- wp:paragraph -->
<p>And <code>crowdsignal</code> shortcode:</p>
<!-- /wp:paragraph -->

<!-- wp:shortcode -->
[crowdsignal poll=7012505 title="Take this awesome awesome poll!"]
<!-- /wp:shortcode -->

<!-- wp:heading -->
<h2>Survey</h2>
<!-- /wp:heading -->

<!-- wp:core-embed/crowdsignal {"url":"https://rydk.polldaddy.com/s/test-survey","type":"rich","providerNameSlug":"crowdsignal","className":""} -->
<figure class="wp-block-embed-crowdsignal wp-block-embed is-type-rich is-provider-crowdsignal"><div class="wp-block-embed__wrapper">
https://rydk.polldaddy.com/s/test-survey
</div><figcaption>Survey oEmbed</figcaption></figure>
<!-- /wp:core-embed/crowdsignal -->

<!-- wp:paragraph -->
<p>And <code>crowdsignal</code> shortcode:</p>
<!-- /wp:paragraph -->

<!-- wp:shortcode -->
[crowdsignal survey=test-survey title="Take this awesome survey!"]
<!-- /wp:shortcode -->

The non-AMP version looks like this (note the first crowdsignal shortcode poll fails to render for some reason):

And here is the AMP version looks like:

Proposed changelog entry for your changes:

• Add AMP support for Crowdsignal/Polldaddy polls and shortcodes.

[jetpackbot]

Thank you for the great PR description!

When this PR is ready for review, please apply the [Status] Needs Review label. If you are an a11n, please have someone from your team review the code if possible. The Jetpack team will also review this PR and merge it to be included in the next Jetpack release.

Scheduled Jetpack release: April 2, 2019.
Scheduled code freeze: March 26, 2019

Generated by 🚫 dangerJS against bed4a8d

[westonruter]

This oEmbed filter should probably be kept in the AMP plugin since Crowdsignal is supported by core directly:

https://github.com/WordPress/wordpress-develop/blob/14cebbe9877c4ef79ea4d79e3d8e1a5581930377/src/wp-includes/class-oembed.php#L65-L67

[kraftbj]

Agreed.

[westonruter]

Implemented now in ampproject/amp-wp#1929

[kraftbj]

Agree the oEmbed filter should remain in the AMP plugin since this is a core oembed.

[kraftbj]

Agreed.

[kraftbj]

Just a note that we'd need to add in support for this function before merging to WP.com.

[kraftbj]

This would be handled by D22154-code .