Recompute vertex capacity when resuming transform feedback. Extract vertex capacity computation into recomputeVertexCapacity() and call it from both begin() and resume() to handle cases where the backing buffer size changes while transform feedback is paused. Add a new WebGL specific test to TransformFeedback to test the expected behavior when making the backing buffer smaller via glBufferData. Bug: angleproject:437706201 Change-Id: I3ac8e1e983ab868e34c1bdac249ce17a40e274f0 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6830709 Reviewed-by: Charlie Lao <cclao@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Kimmo Kinnunen <kkinnunen@apple.com>