Work around firefox webextensions bug

[DCNick3]

Importing gloo_timers in firefox webextension's content script results in an error: LinkError: import object field '__wbg_clearTimeout_65417660fe82f08d' is not a Function

It actually seems to be a firefox bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1787770

This can simply be worked around by refering to timer functions using window object (setInterval -> window.setInterval) which this PR does. I do not think this would impact users outside of webextensions in any way, as window.setInterval and setInterval are the same functions in usual context (but apparently not in content scripts...)

[DCNick3]

Well, looks like this work around is not good enough. While the wasm module does instantiate fine, it still raises an error TypeError: 'clearTimeout' called on an object that does not implement interface Window. when the function is actually invoked.

[DCNick3]

Now this should work. Instead of using window object to refer to the function I make wasm-bindgen generate a wrapper around the desired function by marking it with catch. This way wasm module does not error out on instantiation and is actually able to use those APIs

[ranile]

It seems as a fix for the Firefox bug is underway. I would say we shouldn't merge this and let Firefox handle it.