Add an ILLinkTrim.xml file for InteropServices.JavaScript.

[eerhardt]

Fix #37775

[marek-safar]

I don't think descriptors are right approach here. Please use linker attributes instead, there is already linker attribute https://github.com/dotnet/runtime/blob/master/src/libraries/System.Runtime.InteropServices.JavaScript/src/System/Runtime/InteropServices/JavaScript/Runtime.cs#L16 which should handle this if does not work we need to fix it

[vitek-karas]

Discussed this offline with @marek-safar . It seems that Runtime is not the main entry point from JS to managed. That exists somewhere else (I don't know where). We should have a descriptor for that entry point. And then Runtime can be pulled in by adding DynamicDependency on that entry point (if needed).

Regarding:
https://github.com/dotnet/runtime/blob/master/src/libraries/System.Runtime.InteropServices.JavaScript/src/System/Runtime/InteropServices/JavaScript/Runtime.cs#L16

This should work if there's something else in the managed code which will pull in the Runtime and enough on it to also pull in the field it's on. I don't know enough about the code here to tell if this is supposed to work or not.

[marek-safar]

LGTM, we'll tweak our approach to use descriptors here (pushed one more here)

[eerhardt]

The only failures are ARM64 timeouts which, according to #37623 (comment), @safern is looking into. Merging now.

[ericstj]

Opened #37823 for arm64 timeouts.