Dashboard Build: Use StaticSiteGeneratorPlugin to build Static HTML

[ockham]

Closes #12127 (this is a simpler version of that PR). Prep work for #12072.

Big props @sirreal who pointed me to the right Webpack plugin for the job 👍

Changes proposed in this Pull Request:

tools/builder/react.js uses static.jsx to produce minimal static markup (HTML) versions of the dashboard (really just "Turn on your JavaScript" notices). It require()s the webpack-bundled version of static.jsx to that end, and attaches renderToStaticMarkup()-produced strings to window, which it then writes to HTML files.

Getting rid of the complexity added by passing information by attaching to window (and thus requiring jsdom etc) is the main objective of this PR. This is achieved by using StaticSiteGeneratorPlugin, which is meant for this kind of thing. In a subsequent PR, I hope to get rid of tools/builder/react.js pretty much entirely. This will make it much easier to base the build system for Jetpack's React Dashboard on calypso-build (see #12072).

Testing instructions:

yarn distclean && yarn
yarn build-client
yarn docker:up

• Verify that the React Dashboard still works (wp-admin/admin.php?page=jetpack#/settings)
• Navigate to /wp-admin/admin.php?page=jetpack_modules
• Disable JavaScript
• See this message?

Proposed changelog entry for your changes:

Dashboard Build: Use StaticSiteGeneratorPlugin to build Static HTML

[matticbot]

Caution: This PR has changes that must be merged to WordPress.com
Hello ockham! These changes need to be synced to WordPress.com - If you 're an a11n, please commandeer, review, and approve D28237-code before merging this PR. Thank you!

[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: June 4, 2019.
Scheduled code freeze: May 28, 2019

Generated by 🚫 dangerJS against 2722d86

[jeherve]

This seems to work well in my tests. I'd love it if @zinigor, who I believe worked on that part of the dashboard in the past, could take a look at it as well. :)

cc @zinigor If you have some free cycles.

[zinigor]

This looks amazing, works well, thank you! Only one thing: can we remove jsdom entirely, or should we go on like this? If we can, feel free to merge this.

[ockham]

Thanks @jeherve and @zinigor for reviewing! ❤️

This looks amazing, works well, thank you! Only one thing: can we remove jsdom entirely, or should we go on like this? If we can, feel free to merge this.

Answered here:

Hehe, I was also hoping to get rid of it 😄 Unfortunately, we're still using jsdom-global in our tests, which in turn depends on jsdom. So I'm afraid we need to keep it for a little longer 😅