get mozjs working on stable/beta channels

[olsonjeffery]

What would this require? There are the feature attributes that mozjs is using.. are they going to be stablized any time soon?

[jdm]

#![feature(core_intrinsics)]
#![feature(link_args)]
#![feature(str_utf16)]
#![feature(unsafe_no_drop_flag)]

core_intrinsics is used to return_addr in the implementation of Rooted; I don't know what the stabilization story is there. str_utf16 is used for str::utf16_units. We use link_args for resolving a problem with Android builds. unsafe_no_drop_flag may not be required any more; I'm not sure.

[Ms2ger]

We need to avoid a drop flag for Rooted and friends.

[llacroix]

How are we supposed to build with those features. It raises an error:

error: #[feature] may not be used on the stable release channel

I would like to simply allow it to build.

[Ms2ger]

We do not support building on non-nightly at this point.

[llacroix]

@Ms2ger as I understand unstable features cannot be used on stable release of rust. I guess I'll have to install the nightly build then.