This makes the code more consistent and allows for the Query
constructor to generate a Serial.

Bug: angleproject:4223
Change-Id: I6cc683b11ed364f13d303f97aa0984e63260953e
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1969061Reviewed-by: Cody Northrop <cnorthrop@google.com>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>