feat(runtime): export a render method from the runtime

[christian-bromann]

What is the current behavior?

It is currently rather difficult to render a Stencil VDOM to a container node. While this is technically not needed by users as you can just use WebAPIs to inject a Stencil element to a page, it helps when integrating Stencil within other environments, e.g. Storybook where you get a VDOM value to render somewhere. Stencil has its own VDOM implementation and we can't just take the one from Preact or other frameworks.

Given that the function is lightweight enough it won't have an impact on the bundle size, as it will be embedded into users bundles.

What is the new behavior?

@stencil/core now exports a render method to conveniently render a Stencil VDOM into a DOM node.

Documentation

stenciljs/site#1518

Does this introduce a breaking change?

• Yes
• No

Testing

Added WDIO tests for this.

Other information

I need this for the Storybook integration.