Translator: Propagate precision to children nodes Similarly to glslang, when the precision of a node is determined, propagate that precision to any of its children that doesn't already have a precision. Ultimately these should only include TIntermConstantUnion nodes. Bug: angleproject:4889 Bug: angleproject:6132 Change-Id: I121231d04c7cf92fc3f07716019ffe88eca48b88 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3075126 Reviewed-by: Tim Van Patten <timvp@google.com> Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>