Remove html5shiv from being loaded

According to #2412945-6: Determine which additional asset libraries should be in the critical path/loaded i/t header (core/drupal, core/dropbutton) it is wrapped inside conditional IE8 comments

Roughly: hook_element_info_alter(), do unset($types['html']['#attached']).

It doesn't work in your Panda theme, because:

    // Allow modules to alter the element type defaults.
    $this->moduleHandler->alter('element_info', $info);

… it's only invoked for modules. I think that's a bug; themes should be able to alter existing elements, even if only to attach their own assets to it. (Or, in this case, to remove it.)

Pinging catch about that.

Asked catch, his response:

16:13:28 catch: WimLeers: are elements cached by theme?
16:15:19 WimLeers: catch: oh………
16:15:26 WimLeers: catch: that is a very very very very good point
16:15:31 WimLeers: catch++
16:15:42 WimLeers: catch: they should be, indeed for that reason
16:16:12 catch: WimLeers: there's an issue somewhere about themes and hook_theme_registry_alter()

So we can fix #6, but we'll have to make sure elements are cached by theme. All render caching already happens per theme (for analogous reasons), so there's no problem there.

Postponing this as well

We may be able to start working on this for 8.1

Here's a patch to remove it from being loaded but leaves it in core.

With patch

Whoops forgot my regex delims

Whoops this is a duplicate now of #1993334: Add HTML5shiv to Stable and Classy only