Ensure IDN domains are in punycode format in extension host permissions

Today in extension dialogs and bubbles, IDN domains in host permissions
are not displayed in punycode format. There is a low security risk that
granting such permission would allow extensions to interact with pages
using spoofy IDN domains. Note that this does not affect the omnibox,
which would represent the origin properly.

To address this issue, this CL converts IDN domains in host permissions
to punycode format.


Bug: 745580
Change-Id: Ifc04030fae645f8a78ac8fde170660f2d514acce
Reviewed-on: https://chromium-review.googlesource.com/644140
Commit-Queue: catmullings <catmullings@chromium.org>
Reviewed-by: Istiaque Ahmed <lazyboy@chromium.org>
Reviewed-by: Tommy Li <tommycli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#499090}