Add test for comment bindings

[ruphin]

This adds a test that is currently failing due to incorrect processing of bindings in comments:

html`<p>${'foo'}<!-- ${'baz'} -->${'bar'}</p>`;

// renders: <p>foo -->bar</p>

Reproduction:
https://codepen.io/ruphin/pen/jJVrXd?editors=1010

[mihaisavezi]

so it's a bug

[jridgewell]

Closed by #882