1717815 - Simplify ThreadActor management of Frames

Status: NEW

(DevTools :: Debugger, task, P3)

Description

[Julian Descottes [:jdescottes] (PTO -> Jan 5th)]

Follow up from the discussion at https://phabricator.services.mozilla.com/D118471#inline-655997

Currently, the ThreadActor holds Frame actors in several maps/objects:

• framesPool a typical pool holding "live" frame actors
• frameActors an array of "live" frame actors, updated more or less in sync with framesPool
• _frameActorMap WeakMap of frame -> FrameActor that holds each and every FrameActor created by the ThreadActor

We should simplify this and try to reduce the duplicated maps/pools/arrays storing identical information.

Note that _frameActorMap is a weakMap but it's probably buggy. The key is a frame and the value is a FrameActor. However the FrameActor has frame as a property. This should create a circular reference which means that this WeakMap is probably never ever shrinking and is just accumulating FrameActors forever.
Edit: WeakMap should support circular references fine, and this shouldn't prevent garbage collection