Update button isDefault/isCancel handling on SC.AlertPane.

If any button specifies isDefault, ignore the default value of this
property on each button and always use the value passed in. This allows
just specifying isDefault on the one button that should be default,
without having to also say isDefault:NO on all the other buttons.

Also do the same for isCancel.
Let insertText handle insertNewline for textareas.
Adds SC.Request.manager functions isPending and isInFlight.

Allows checking if a response is in the pending or inflight queues.
Allow SC.State's to disallow a state transition.

Added a stateCanBecomeExited function to SC.State. During
SC.StatechartManager#gotoState, all states that will be exited will have
this function called. If any of them return NO, the state transition will
be canceled.

Conflicts:

	frameworks/statechart/system/state.js
Ensure text field hint line-height gets set correctly.

Call _fixupTextLayout when appending to the document and when hint is shown
so the right line-height is applied.

_fixupTextLayout is called from didCreateLayer, but at that point the hint
may be hidden and have an incorrect outerHeight().
Remove _recalculateDivider flag from SC.SplitView.

This flag does not serve any purpose. Having a percentage value for the
default thickness is already handled and does not require renderLayout
to be executed again.

In addition, this was causing a bug when double-clicking on the divider
as the first action after the split view was rendered. The new thicknesses
would be set, then renderLayout would execute because of this flag,
resetting them to the back to the default.
Fix issue with sending statechart events while state transitioning.

sendEvent had a typo which allowed events to be sent while in the middle of
a state transition. Fixing that revealed that now events sent during state
transitions would be queued but never sent (at least until another event
was sent).
Makes invokeNext trigger the next run of the run loop if none is scheduled.   This makes invokeNext the appropriate method to use when needing the DOM to be up-to-date before running code against it.

Previously, invokeNext functions would not run until the next run loop occurred, which if there were no events or timers, might mean that the code won't run for a long time.  While invokeLast lets you put code at the end of the run loop, the DOM will not have yet been updated and invokeLater is risky to use at small intervals, because if the interval is too small, the invokeLater code will run in the current run of the run loop and again the DOM will not have been updated.  Instead, invokeNext now ensures that the run loop completes execution and schedules an immediate timeout in order to allow the browser to update the DOM.

This works with the timer additions to the run loop, so additional run loops only run once even if there is an invokeLater expiring at the same time as the invokeNext timeout triggers a new run loop.

- Includes unit test.
- Fixes bug in previous unit test that left a run loop unfinished.
Fixes problem with previous invokeNext() change.  If a run loop timer is fired in the current run loop and therefore unschedule's itself, it didn't reset the internal _timeoutAt variable which meant that attempting to schedule a new run loop timer would not work.

Includes unit test.
Bumping to SC 1.9.0.9.