Remove indexOf tests for thread existence in doneThreads. Maintain a
list of null and thread objects mirroring the index position of threads
that are done in runtime.threads. Filter out null values after
filtering out done threads from runtime.threads.
This has a small side effect that threads that normally became DONE and
were added to doneThreads before being removed or restarted will not be
in doneThreads in this version. Restarted threads (_restartThread) do
not appear in this version but new copies will be in Runtime
this.threads supporting glow and monitor updates. Removed threads
(_removeThread) do not appear in this version if they are removed after
they were seen as DONE by the prior version. Threads removed before
they are seen as DONE do not appear in doneThreads in the prior or this
version.
Threads that are removed before normally becoming DONE do not appear in
doneThreads in either case. Threads that are restarted before the loop
checks if the thread is done do not appear in doneThreads in either
case.
- Accumulate extension info while deserializing JSON
- Install extensions (if any) before installing target(s)
- Merged 'install' steps of the "add sprite" and "load project" paths
Since we will only have builtin extensions for a while, the
more-complicated, watchdog-based extension duplication prevention has
been replaced with one that treats the extension URL as equivalent to
the extension ID. This is true only for built-in extensions, so once we
start supporting third-party extensions we will likely need to bring
back the watchdog (commit e4381b4693) and
the more-complex duplication prevention (commit
670e51d335).
The code here should be treated as a last resort: ideally the GUI should
check if a particular extension is loaded (maybe by calling the
Extension Manager's new `isExtensionLoaded` method) and avoid calling
`loadExtensionURL` if it is.
If an extension attempts to register with the same ID as another
extension which has already registered, the new registration is refused.
If the extension is in a worker and no other extension is successfully
registered by that worker, the watchdog system will terminate the
"empty" worker.
If an extension worker does not complete initialization in a reasonable
amount of time (currently 15 seconds) then the worker will be
terminated. A complete initialization includes registering an extension.
