Templates: commenting out <xxx:> tag breaks component's template

[aommm]

Whenever this code is present anywhere in a component's template, it breaks:

<!-- <my-view-here:> test content-->

The entire component is then rendered as ">", as can be seen when inspecting the generated DOM.

I understand that this is a minor bug, but I thought it worth reporting nonetheless!

[dadisn]

Same as #468.