GC: do not trace context slots above stack pointer
GC: do not trace context slots above stack pointer

Speed-Pad/online,bertfreudenberg/SqueakJS,sebastianconcept/SqueakJS,fmateoc/SqueakJS,Speed-Pad/online,sebastianconcept/SqueakJS,sebastianconcept/SqueakJS,fmateoc/SqueakJS,fmateoc/SqueakJS,fniephaus/SqueakJS,the-impossible-quiz-revisited/the-impossible-quiz-revisited.github.io,Speed-Pad/online,fniephaus/SqueakJS,bertfreudenberg/SqueakJS,bertfreudenberg/SqueakJS,fniephaus/SqueakJS,the-impossible-quiz-revisited/the-impossible-quiz-revisited.github.io,bertfreudenberg/SqueakJS,fniephaus/SqueakJS,the-impossible-quiz-revisited/the-impossible-quiz-revisited.github.io,the-impossible-quiz-revisited/the-impossible-quiz-revisited.github.io,fmateoc/SqueakJS