This commit makes the fullsample option for viewport renderings always on: Render > OpenGL Render Options > Full Sample. (The UI still allows users to set this, so we will need to revisit this before 2.8 releases). Even in computers that can handle MSAA we had issues. The way Blender gpu_* implementation is handling anti-aliasing is buggy. For example, in Blender 2.7x if you have depth of field in a viewport with multi-sampling, the DoF gives us jagged edges. Since Eevee uses framebuffers for a lot of things, this issue was leading to very visible buggy render in some computers, and more subtle inconsistent buggy renders in others (easy to test with the depth of field in Eevee).