Tests stepping out from javascript to a wasm caller

Running test: test
Instantiating.
Running exports.main.
>>> First round
Paused at:
function pauseAlternating() {
  if (pause) #debugger;
  pause = !pause;

Paused at:
Script wasm://wasm/15df010e byte offset 53: Wasm opcode 0x0b (kExprEnd)
Paused at:
instance.exports.main()#

exports.main returned.
After stepping out of the last script, we should stop right at the beginning of the next script.
>>> Second round
Paused at:
#instance.exports.main()

exports.main returned.
The next cycle should work as before (stopping at the "debugger" statement), after stopping at script entry.
>>> Third round
Paused at:
#instance.exports.main()

Paused at:
function pauseAlternating() {
  if (pause) #debugger;
  pause = !pause;

Paused at:
Script wasm://wasm/15df010e byte offset 53: Wasm opcode 0x0b (kExprEnd)
Paused at:
instance.exports.main()#

exports.main returned.
