make the Object.create assertion more specific
Merge pull request #2511 from emberjs/more-ie8-oo-create-fixes

make the Object.create assertion more specific
Merge pull request #2509 from seanpdoyle/add-tests-number-transform

Add Test Coverage for `DS.NumberTransform`
[BUG] Transform `{NaN,Infitity,-Infinity}` to null

https://github.com/emberjs/data/pull/2509#discussion_r20898264

Serializing and Deserializing invalid numeric `JSON` (`NaN`,
`Infinity`, `-Infinity`) should result in `null`.