Avoid hard-coded heights and positions in about:tor. The "update needed"
  arrow is now constructed from 4 elements instead of 2 and the info.
  "bubbles" use table layout instead of hard-coded heights.
Set the CSS z-index so that text will be in front of the status image
  (onion image) and the "update needed" arrow.
Use "let" instead of "var" in the about:tor JS code.

We previously spoofed the `intl.accept_languages` value to "en-us, en"
but with the update to ESR 38 Firefox does not like the lower case
country code anymore. See: https://html5.org/r/8458 and
https://bugzilla.mozilla.org/show_bug.cgi?id=889335 for the reasons
behind that.

We adapt our code accordingly and set the default value to "en-US, en"
now. This fixes #13277 as well.

Thanks for this patch, cypherpunk.

Adding this fixes problems such as the lack of "Tor Browser"
in the left side of the URL bar for pages such as about:config.

This reverts commit 495c0079.

This reverts commit edeaca15.

This fixes 16722 as well and resets the toolbar UI to kill
"Share this page", but that still requires another restart :/.

This is basically Mike's idea and code.

Account for an nsIExternalHelperAppService.idl interface change
(the parameters to the doContent() method were changed between
ESR31 and ESR38). See Mozilla bug #903022.

Patch by Pearl Crescent

Import aboutDialog.dtd and aboutTor.properties from Transifex.
Improved import-translations.sh to check that all .dtd and
  .properties files are imported.
Work around a Transifex issue that caused some entities to be
  encoded twice.

Check the state of the active update (if any) and open the update prompt
in the correct mode.

It is now obsolete. Firefox now properly disables session store if private
browsing mode is enabled.

We avoid using https://127.0.0.1 as update URL in order to omit scary
Tor warnings (see: #13129).

Removed old, unused default preference values.

(This updates and consolidates offline cache code as well.)

This reverts commit f35b2f85.

Version bump, CHANGELOG update and translations update.

This reverts commit 9690abf0 for the
stable Tor Browser series.

Overlay the about:addons page to avoid a direct dependency
on entities that are defined in Torbutton.