assignDeep copy plain objects values instead of reference

[cherifGsoul]

For #150

[justinbmeyer]

Have you tested this against canjs/canjs? If everything passes, this looks good to me. This feels like something downstream might break.

[cherifGsoul]

@justinbmeyer I edited the code and tested it with canjs/canjs and all tests pass, can you please review it?

[phillipskevin]

This won't solve the original issue since it was using a DefineMap. Is that being handled somewhere else?

[phillipskevin]

@cherifGsoul, can you add tests for each of the scenarios that is failing in other repos?

The tests I can think of:

• a test for the original issue (assign-deep deep copy)
• a test to replicate the can-map-define issue where a constructor is passed as a property (assign-deep with a constructor)
• a test to replicate this cyclic objects test where the same object is passed twice on the source so the same copied object should be on the destination twice (assign-deep with duplicate objects

I think you were also running into an issue with type: "compute", but I'm not sure what it was. That might need a test also.