Fix some style errors.
Implement TimingFunction.createFromString.
Parse steps(), cubic-bezier()
Avoid sorting keyframes every time we sample.
Merge pull request #22 from dstockwell/keyframes

Avoid sorting keyframes every time we sample.
Rename exists() to isDefinedAndNotNull() for clarity

No functional change.
Fix use of isDefinedAndNotNull()

When processing arguments to API functions, we generally want to test only
whether a variable is defined. We then rely on the regular JavaScript type
conversion rules for handling values of the wrong type, including null.
Introduce a new isDefined() helper for this case.

Also fix the test for a parent in TimedItem(). This was broken in
2998dbbd9c35c748cba75ee9990a621ae60f2fa9, which caused test-parent to fail.
TimedItem must initialize timing variables before calling updateIterationDuration

TimedItem.updateIterationDuration() uses parent, _startTime, _timeDrift and
_locallyPaused, so these must be initialized before the method is called.

Also remove superfluous logic to (incorrectly) set endTime, as this is done
correctly in updateIterationDuration().
The intrinisic duration of an empty par group should be zero

See
https://dvcs.w3.org/hg/FXTF/raw-file/tip/web-anim/index.html#the-intrinsic-duration-of-a-parallel-animation-group

Currently, the intrinisic duration of an empty par group is -Infinity, because
that is the value of Math.max.apply([]).
Add a test for reparenting
Add tests for animation start time
Merge pull request #15 from steveblock/startTime

A couple of minor fixes, and some tests to document the odd behaviour regarding default start times in parent groups
Add some tests to the test harness.
Merge pull request #23 from shans/addTests

Add some tests to the test harness.
Cleanup color test.
This was triggering when parentGroup.iterationTime == 0, which was causing forward fill of reversed animations to fail (test-start-time.html and test-start-time-tierations.html picked this up).
refactor internal representation of length to take into account percent as well; support mixing percent and pixel via -webkit-calc.
test case
Add test case to harness
improve test case