As of Firefox 153.3.0esr, Services.scriptloader refuses jar:file: and file:
URIs unless allowUnsafeURL is passed (Mozilla bug 1974213), so no plugin
loads: bootstrap.js fails with "Trying to load untrusted URI", then
"Plugin ... is missing bootstrap method 'startup'".
Pass allowUnsafeURL when loading a plugin's bootstrap.js and prefs.js,
and preference pane scripts, and temporarily enable
security.allow_unsafe_subscript_loads, which covers loads from plugin
code outside the bootstrap scope.
Also add a test that installs a fixture plugin that loads a script from its XPI
and sets a default pref.
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Co-authored-by: Dan Stillman <dstillman@zotero.org>
