Our context virtualization code would try to optimize this case
and leave the current context bound when possible. This has the
side effect of leaving the current surface bound too, even if
it was deleted.

During Chrome's window resizing, it deletes the window, calls
eglMakeCurrent with null and then recreates the window. This
causes an error because the window still exists because it was
left current in ANGLE.

Bug: chromium:1167718
Change-Id: I857be88be48dfa9c0dd9173f235e155e727e3014
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2637717Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>
Commit-Queue: Geoff Lang <geofflang@chromium.org>