richard authored Jun 26, 2018 and Georg Koppen committed Jun 29, 2018

Fixup for 26039.  WebExtension extensions can't read/write prefs, so the
base contents of extension-overrides.js are completely unnecessary.  The
WebExtension versions of noscript and httpseverywhere seem to be nearly
complete re-writes (noscript in particular is much simpler) so our
custom options appear to be no longer required (though a complete audit
of noscript should probably be done just to be sure we don't need to fix
any bad behaviour).

The updated build script for tor-browser now dumps all of the
build-determined prefs (pluggable transport strings, localization
options) into a generated-prefs.js file created at build time, which is
then appended to 000-tor-browser.js as before.

The pdfjs option is no longer needed since the disableRange option seems
to break pdfjs altogether in latest ESR60.  Also, setting the user pref
in 000-tor-browser.js does not work since pdfjs overwrites it with its
own value (any future patch setting pdfjs options needs to modify the
default values table)