[Bug] Support window.print()

[yoasif]

Steps to reproduce

1. Navigate to https://www.w3schools.com/jsref/tryit.asp?filename=tryjsref_print
2. Tap "Print this page"

Expected behavior

Print dialog appears.

Actual behavior

Nothing happens.

See also #10217

Also in issue in Reference Browser.

Device information

• Android device: Pixel 2
• Fenix version: latest nightly

┆Issue is synchronized with this Jira Task

[makotokato]

Fennec didn't support this.

• https://bugzilla.mozilla.org/show_bug.cgi?id=739038
• https://bugzilla.mozilla.org/show_bug.cgi?id=1247609

[neontorrent]

Any update on this?

[karlcow]

Another duplicate for this.
webcompat/web-bugs#77486

[headbank]

An observation made in #10217 that is probably even more relevant here:

While we await the actual print functionality's arrival, the current state of this hurts web developers. If I understand correctly, window.print is totally MIA, so a method in which it is called will just quietly puke, which may clobber subsequent js code. (Whether window.print() should really only be called in isolation, or always wrapped in a try/catch, is arguable but besides the point.)

Even when the user-facing upshot is limited to "Clicking the Print This Page button and nothing happens", it's still likely to be assumed by many users that the site is broken and the web dev is to blame.

This is driven by the twin likelihoods (IMHO) that (a) most users and (b) a great many web developers will tend to assume that any smartphone browser does support printing. Fenix really is an outlier in this respect, as many people in the other ticket have pointed out.

I would very much like Fenix to give UI feedback to the user that printing is currently unsupported.

[karlcow]

There is also https://bugzilla.mozilla.org/show_bug.cgi?id=1659818

[headbank]

There is also https://bugzilla.mozilla.org/show_bug.cgi?id=1659818

Which in turn appears to await https://bugzilla.mozilla.org/show_bug.cgi?id=1659819
(If I have understood what's been said there)

[headbank]

Stuff is happening: https://bugzilla.mozilla.org/showdependencygraph.cgi?id=1659818

The top two ellipses went from green to grey (resolved) this morning :)

[cpeterso]

Closing this issue because we're tracking window.print in https://bugzilla.mozilla.org/show_bug.cgi?id=1659818