LiveView Native Clients: template comments caused stack trace

[bcardarella]

The following:

<!-- ignore this

<!-- ignore this too -->

While this has two opening comment tags the 2nd one should be ignored as it is technically commented out. The first open comment tag should comment all the way until it reaches the first closing comment tag. This current results in a stack trace:

[carson-katri]

This should be raised in core, which handles all document parsing.

Also, nested comments are not valid in HTML. Should we be allowing that anyways?