Translator: Make precise-ness a property of AST nodes Instead of creating a "set of precise nodes", the nodes themselves are marked precise. This change is preparation for another change that overhauls precision propagation through the nodes, and which would also be storing the promoted precision in the nodes. Bug: angleproject:4889 Change-Id: Ieec8864be5cd2e95ed6fb4d90b367946d9f33fa1 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3065569 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Tim Van Patten <timvp@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>