Fixed regression introduced in 3.10.0, with stale facade properties sticking
around in the case of "no subscribers".

Added unit tests for both the subscriber and no subscriber case.

All unit tests pass:
✔ [Total]: Passed: 10859 Failed: 0 Total: 10954 (ignored 95)

Slider functional tests pass.
Slider examples work manually.

This impacted slider's thumbMove defaultFn which was using a "source" property
added to the facade to figure out whether to set the value or not, and
commonly had no listeners (only surfaced by manual testing, which was why
it got missed - unit and functional tests all passed).
Added on subscribers fresh facade test also
Added on subscribers fresh facade test for real this time
Fixed issues due to Y.DOM being undefined when event-base was attached in rare use cases

Fixes #2533242

The `YDOM = Y.DOM` alias we added in 3.7.3 would end up being undefined
in certain custom module dependency use cases, which would result in
`nodelist.on()` failing to attach listners.

In order to bring out the issue, all the following need to apply:

a) Custom module with node-base dependency
b) node-base repeated in use statement
c) Module dependencies for custom modules not provided to YUI()
   instance (not available to loader).

NOTE: This is not the root fix. The root fix is in loader somewhere, but
given the catch22 complexity between node-base and event-base, and the rareness
of the use case, this seemed like the better way to go.

Confirmed that the unit test added passes with this commit, and fails starting
with 3.7.3.
Merge branch 'slider-regression-event-fix' into dev-master
Build for event fix for slider regression. Cleaning up stale facade props

All tests pass:
✔ [Total]: Passed: 10860 Failed: 0 Total: 10955 (ignored 95)
Merge branch 'event-dom-attach-order-fix' into dev-master
HISTORY.md for YDOM alias fix
Fixed trailing whitespace/longline jshint issues while building for YDOM fix
Build for YDOM = Y.DOM alias fix.

All tests pass:
✔ [Total]: Passed: 10861 Failed: 0 Total: 10956 (ignored 95)

Also ran **all** tests through Yeti on FF/Safari/Chrome/iOS.

NOTE: This commit also contains build files with trailing whitespace
and longline fixes for jshint, since we're building src/event.

The only functional (and hence -min file) change is in event-base though.