Add RelaxedPrecision decoration to function-call temp vars.

This is really same basic issue as http://review.skia.org/446640. We
were creating a temp variable but ignoring its type's precision.

Change-Id: I9a5fedd7ada864d36757fc196f42ff95bac7d706
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/446718
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
16 files changed