JSAutoRequest is required before calling into most JSAPI methods, for GC
reasons.
Calling it is required and fragile as one must not forget.
Further, SM52 and later make manipulating JSContext* dangerous as that
can cross Compartment(Realm in SM68) barriers (and ScriptInterface now
matches a Compartment).
The solution to both problems is to avoid using JSContext* in 0 A.D.
itself. To achieve this, a Request class is introduced, and must be used
to access a JSContext* from a scriptInterface. Further, Request is
passed to other ScriptInterface functions isntead of JSContext*, making
it obvious that the caller has already called it, reducing errors and
redundant JSAutoRequest calls.
Only JSNative functions now get a naked JSContext* without protection,
but the likelihood of forgetting a request is lower since many
ScriptInterface functions now expect it.
JSContext* is directly passed to JSAPI functions only.
Part of the SM52 migration, stage: SM45 compatible
Based on a patch by: Itms
Tested By: Freagarach
Refs #4893
Differential Revision: https://code.wildfiregames.com/D3088
This was SVN commit r24176.
ee0d204bf6