Clean up `split_args` a bit.
Clean up `split_args` a bit.

- It was odd to have it memoize internally but accept an arg.
- Simpler just to call it once in `initialize`.
rspec/rspec-mocks,telekomatrix/rspec-mocks,zephyr-dev/rspec-mocks,h4ck3rm1k3/rspec-mocks,zephyr-dev/rspec-mocks,AEgan/rspec-mocks,h4ck3rm1k3/rspec-mocks,rspec/rspec-mocks,rwz/rspec-mocks,ducthanh/rspec-mocks,edwardpark/rspec-mocks,telekomatrix/rspec-mocks,maclover7/rspec-mocks,ducthanh/rspec-mocks,edwardpark/rspec-mocks,maclover7/rspec-mocks,rwz/rspec-mocks,AEgan/rspec-mocks