Make VertexBinding's member variables private The patch decorates all members in VertexBinding as private and limits access to them only through getters and setters. This makes it easier to debug and keep track of any assignments to the class members. BUG=angleproject:2062 TEST=angle_end2end_tests Change-Id: Iddd49063d060f136bc9cf11c313a5af0931d433c Reviewed-on: https://chromium-review.googlesource.com/530786 Commit-Queue: Olli Etuaho <oetuaho@nvidia.com> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>