Ignore focusin/focusout events on iframes

In IE11, when the focus moves into an iframe, focusout is
emitted on the element that used to have focus (which is correct)
and focusin is emitted on the iframe (which is incorrect).
Even worse, when the focus moves between two iframes,
focusout is emitted on one and focusin is emitted on the other,
while really from the perspective of the main document
nothing is happening.

This confuses the focus change code in ve.ce.Surface,
so ignore focusin/focusout events emitted on an iframe.

Ignoring these events fixes the bug where, in IE11,
the language inspector would close as soon as you
opened the language selection dialog.

Change-Id: I1236887f927df77e3bc2eaa9ec4ba07a69e3beaa
Merge "Ignore focusin/focusout events on iframes"