[whatwg] Global script clean-up jobs and "spin the event loop"

"Jump to a code entry-point" essentially maintains a stack of entry
scripts, to determine the "outermost" script in order to know whether to
run the global clean-up jobs.  This assumes that this algorithm will always
be entered and exited as a stack: an invocation of the algorithm must
always complete after any later invocations.

Does this hold even in the face of multiple nested invocations of "spin the
event loop" algorithm?  That algorithm doesn't seem to try to guarantee any
kind of stack-like behavior.

-- 
Glenn Maynard