Test for step-into remote async task

Running test: test
Setup debugger agents..
Pause before stack trace is captured..
Run stepInto with breakOnAsyncCall flag
Trigger external async task on another context group
Dump stack trace
boo (target.js:1:22)
call (framework.js:3:2)
(anonymous) (target.js:0:0)
-- remote-task --
store (utils.js:2:25)
foo (source.js:1:13)
(anonymous) (source.js:2:6)
