Don't stub prototypes

* Stubbing the prototype of the class under test is effectively the same as testing private functions, which is covered by #749.
* Stubbing the prototype of a library that isn't under test should be unnecessary. Anything we need to stub in a controller should be passed in as a parameter to the constructor.

No files or tests are identified. Search the repository's tests for prototype stubbing, then determine which stubs concern the class under test or libraries and replace the applicable setup with constructor-provided parameters; done means the targeted prototype stubs are removed without losing test coverage.

Written by the indexing model from the issue text.