Whether IdPassProgram.dispose has run.
Deletes the GL program (§83). Idempotent; live context only.
Uploads one encoded id colour (encodePickId's four floats).
Makes this the current program. Once per pass, before any upload.
StaticcreateCompiles and links the id program on gl — UnlitProgram.create's
contract: throws SHADER_COMPILATION_FAILED (§89) with the driver's log
attached, deletes shader objects on every path.
The compiled id program —
UnlitProgram's creation and upload discipline over the two sources above. Compiled lazily by WebglPickingService on its first pass, never at registration or service creation.