windows opengl: Provide the context to textures everywhere where we have it.

Change-Id: Ib820326fdc752d0893840bad3eb7f1369469f796
Revert "vcl: Fix crash when requesting coordonnates for empty texture"

Not necessary any more.

This reverts commit 2195500d40055a182c573da074e61ddf0a2b4d5a.