Test PerformanceObserver handling of entries added while in callback.

On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".


PASS PerformanceObserver 1 callback fired
PASS list.getEntries().length is 1
 - mark1
PASS PerformanceObserver 2 callback fired
PASS list.getEntries().length is 2
 - mark1
 - mark2
PASS PerformanceObserver 1 callback fired
PASS list.getEntries().length is 2
 - mark2
 - mark3
PASS PerformanceObserver 2 callback fired
PASS list.getEntries().length is 1
 - mark3
PASS successfullyParsed is true

TEST COMPLETE