I think there are 2 independent things here:

1. load and inline styles: they can come either from styles/stylesUrl annotation or be embedded in the template
2. adjust the styles for shadow dom emulation

1. needs to be done independently of the shadow dom emulation: We don't inline for native shadow DOM right now, but we should, as otherwise view instantiation gets asynchronous (we would need to wait for the <style href="..."> elements have been loaded (see Wait for included css to be fully loaded before instantiating a component / finishing the compilation #1694). This needs to happen before any compile step. I would vote for letting the TemplateLoader do this already, so a build step that inlines the template would automatically also inline the styles.

2. is depending on the shadow dom emulation emulation and can assume that styles are already inline in the template as a <style> element. I.e. this can be a regular compile step.

A side effect of this would be that the CompileStepFactory no longer needs subTaskPromises, as they were only used by the compile step that inlines styles. Also, ShadowDomStrategy.processStyleElement would always be synchronous as it would not do any loading.

@vicb Could you change the code accordingly?

This needs to happen before any compile step

Why ?
I think we can parallelize compilation & css loading / inlining, what would be wrong with that ?

TemplateLoader

Should we rename it to ViewLoader now and have loadTemplate and loadStyles methods ?

2. Not sure to get why we need to delay the compilation ? Could this be updated in a second step.

May be we should chat today to clarify this ?

talked to @mhevery: Please inline first and then start the compile process. This is ok for production as in that case we would inline the html and styles in a build step so there would be no xhrs.

Thanks for the feedback, I'll update tomorrow.

@tbosch could you please review this PR ?

Currently I have implemented what we've discussed yesterday: move the styles from the annotation inside the template before the compilation.

In order to keep the PR reviewable, I'll address the remaining stuff (see TODO in the description above) as separate PRs.

Looks good. Please add link to the PR that will make ShadowDom strategy sync.
And please add fixes #1694 to the last commit as well.

Needs rebase though...

@tbosch #1694 will be fixed as part of the next PR (strategies are still async in this one)

landed as ac3e624 + previous commits

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