IE11: Customizer always sends you into the theme-selector screen

[Clorith]

In IE11, when loading the customizer, or when installing and previewing a new theme, you are always sent into Themes > WordPress.org themes screen.

To elaborate:
From any screen in wp-admin or the admin bar, click Customize (or via the menu, Themes > Customize), the customizer loads, then moves you automatically o the Theme selector screen to find a new theme from WordPress.org

Second scenario, when you've picked a theme, you click "Install & Preview", after waiting for the theme to download (should this line have said downlaod and preview instead of install?) you are once again dropped into the screen to select a new theme to download and preview.

[westonruter]

For some reason IE11 an input event fires on the search field even when the panel isn't expanded. Easy fix here: ignore events when the panel is not expanded.

@Clorith please test 42556.0.diff​.

[Clorith]

42556.0.diff​ does the trick!

[SergeyBiryukov]

42556.0.diff​ works as expected.

[westonruter]

In 42187:

Customize: Prevent themes panel from auto-expanding in IE11.

In IE11 the input event erroneously gets triggered initially without any user input.

Amends [41648].
See #37661.
Fixes #42556 for trunk.

[westonruter]

In 42188:

Customize: Prevent themes panel from auto-expanding in IE11.

In IE11 the input event erroneously gets triggered initially without any user input.

Amends [41648].
See #37661.
Fixes #42556 for 4.9.