ESR52 includes this commit:
https://hg.mozilla.org/mozilla-central/rev/f8cf0fe7c810
which changes the compiler used from 'c++' to 'g++'.

We need to allow JavaScript on feed pages explicitly. Otherwise are
those pages broken on higher security levels.

Remove the SocksPort and ControlPort configuration from
torrc-defaults. Tor Launcher configures the ports via args
when starting tor, and we must avoid conflicts.

Also, strengthen the warning to users about not editing
torrc-defaults.

Use chmod to grant permission for "other" to access files within
TorBrowser.app.

Account for the changes Mozilla to support localized default bookmarks
(see: https://bugzilla.mozilla.org/show_bug.cgi?id=1235107).
Currently, Tor Browser uses the same bookmarks for all locales.

We are not showing the language prompt on first start anymore. Thus, the
multi lingual setup has stopped working for nightlies. We remove that
experiment until we solve #17400 properly or have a new prototype to
try.

Selfrando is a new defense against code reuse attacks developed by the
Redactor and Readactor++ people. We should give it a wider testing
audience by including it in the alpha series.

This is currently only available for 64bit Linux builds, though.
Supporting other platforms and architectures is work in progress.