docs: Fix a few typos

docs: Fix a few typos

There are small typos in:
- spec/spec/animation/Runner.js
- src/animation/Runner.js
- src/animation/Timeline.js

Fixes:
- Should read `successful` rather than `successfull`.
- Should read `transforms` rather than `tranforms`.
- Should read `resetting` rather than `reseting`.
- Should read `overwrite` rather than `overwfrite`.
- Should read `morpher` rather than `morepher`.
- Should read `declarative` rather than `declaritive`.

Signed-off-by: Tim Gates <tim.gates@iress.com>