Little Observers
performMicrotaskCheckpoint
added __forceCollectObservers for testing
fix performMicrotaskCheckpoint
more fix performMTC
All performMTC to work in testing mode for Object.observe
added testing Observer.__errorThrownDuringCallback
Description of v3 APIs
Fix typos
fixed typoes
re-organize tests
disconnect tests
reset tests
fix PathObserver never unobserves bug
support observing values on prototype for PathObserver