Use strings for observed properties are easier to debug
Trim whitespace
Add missing calls to cleanTrackedObservers()
Log the destruction of classes more
Use a multiplication expression (ref * premultiplied number) for percentages
Add target argument to the value changed callback

In the old system, the target was implicitly known by the called function,
but now we need HSSObject to take care of most of these, so we need it to
be a parameter.
Remove redundant call to set the computed value
Fix firing of events
Add functions to convert from event type to string and back
Add hostProperty property on object and parser node
Fix memory issues related to observing and tracking
Set scope on the object definition when not a DO
Remove obsolete function
Fix using percentages on color stops
Remove too noisy log line
Make destruction log line more useful for debugging
Iterate over inner borders in reverse
Reuse the same instances for all the object context changes
Reorder functions so that they are the same as in the implementation
Initialize ivars