Enable asserts when running tests
Begin compositing from the last replace operation

This avoid a bug where we were attempting to composite on top of an undefined
underlying value.
Merge pull request #459 from alancutter/renameBeforeValue

Rename beforeValue and afterValue
Merge pull request #458 from dstockwell/asserts

Enable asserts when running tests
Merge pull request #455 from alancutter/inlineStyleFacade

Allow editing of inline styles during an animation
Added asserts and wrapper methods