Doing GC calls in the entry path (when JavaScript calls into MicroPython at
the top/outer level) can lead to freeing of objects which are still in use.
This is because the (JavaScript) objects are referenced in the input
arguments to the C functions and they are not yet converted to full proxy
objects and not yet tracked properly by the live-object tracker.
Signed-off-by: Damien George <damien@micropython.org>