Typescript fix demo and shadow

[valdrinkoshi]

Fixes #18 by looking at the shadowRoot host to retrieve internal state info.
Updates demo to use only Custom Elements V1 and ES modules instead of HTML Imports

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[aomarks]

Change looks good, but tests are now failing in the same way that I reported in #17 (e.g. https://app.saucelabs.com/tests/0d211355b0754f178a5c5c900c8ac5c3#0) but on other browsers too... it seems like this could be some kind of timeout issue? I did try bumping max-duration in my PR, but it didn't seem to make any difference (I couldn't actually figure out what system reads that parameter).

[aomarks]

Merging, since the test failures are flakes (note different browsers fail on pr and push, and all the videos show that 100% of tests actually passed).