The TransformFeedbackVk::onBeginEnd() method wasn't calling updateQueueSerial(),
which was causing CommandGraphResource::hasChildlessWritingNode() to use an old
mCurrentWritingNode, which had already been freed (i.e. Visual Studio showed it
pointing to memory that is 0xdddddddd--which means that mCurrentWritingNode has
been freed, but is still being used).

Unfortunately, there are still other crashes affecting these tests, but they
are the same set (and yes, there are multiple, and they are random) that cause
most of the "KHR-GLES3.copy_tex_image_conversions.required.*" tests to crash).

Bug: angleproject:3674
Change-Id: I5cd44018ea0beb25cb218e562d5b863be6cbd450
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1742972
Commit-Queue: Ian Elliott <ianelliott@google.com>
Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>