Fixed checks for drawable when rendering.

Fixed check for drawable to work properly for context views as well (not
  just render views). Fixing logic added by commits c23602752 and
c8736fa3. vtkSMViewProxy should not have code that works with
vtkPVRenderView alone. This fixes LoadStateMultiView test issues on OsX.

Change-Id: I8ef899cb47fafae75fa57ef0a603c7a12e48e00e
Merge topic 'fix_osx_test_issues' into next

47198123 Fixed checks for drawable when rendering.