No real changes, just clean up wxCustomRendererObject in Cocoa wxDVC.

No real changes, just clean up wxCustomRendererObject in Cocoa wxDVC.

The variables tableColumn and item are unneeded in this class so remove them.

Use static_cast<>s instead of C casts.

Avoid repeating oneVeryLongVariableName->anotherEvenLongerVariableName->
somethingElse->andSoOn multiple times, temporary variables are allowed in C++.

Also don't call wxDataViewCustomRenderer::GetSize() twice unnecessarily.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62389 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775