Fix description for recursive wsdl with extended element

[mastodon0]

I found a bug when using a WSDL that includes recursive types combined with extended elements.
The description of recursive objects would be empty because _.defaultsDeep creates copies of child objects. Using _.defaults only creates the necessary object references and solves the issue.

The testcase shows the problem: We have the types Person -> Department -> Person (HeadOfDepartment)
personDescription.Department.HeadOfDepartment would be an empty object, but should be the same object as personDescription

[coveralls]

Coverage remained the same at 93.37% when pulling 99ce4e1 on mastodon0:master into be79b70 on vpulim:master.

[jsdevel]

thanks @mastodon0 !