Add a custom firefox binary.

component/firefox/buildout.cfg

@@ -47,6 +47,11 @@ script =
   ))
     os.fchmod(f.fileno(), 0o755)
 
+[firefox-wrapper-custom]
+<= firefox-wrapper
+wrapper-name = firefox-custom
+part = ${firefox-custom:location}
+
 [firefox-wrapper-60]
 <= firefox-wrapper
 wrapper-name = firefox-60
@@ -69,7 +74,12 @@ part = ${firefox-51:location}
 # installed in ${buildout:bin-directory}.
 # Installing ${firefox:} is not enough, because wrapper setting $LD_LIBRARY_PATH
 # would not be created.
-<= firefox-52
+<= firefox-custom
+
+[firefox-custom]
+<= firefox-download
+x86 = none
+x86-64 = https://softinst81356.host.vifib.net/public/backup/firefox-70.0a1.en-US.linux-x86_64.tar.bz2 9fb9534d2022250d73d2cf503d7fd554
 
 [firefox-60]
 <= firefox-download