Store float value for settings in SkSL v2

If you used 'in float foo' in a runtime effect it would always have the
value cast to an int. I don't think we saw this in .fp files because
the cpp generation handled those values directly (if I remember correctly)

Just uses a union of float and int, differentiated by fKind, so that it
compiles in standalone mode (vs. using SkFloat2Bits, etc.).

Also updated to add a unit test.

Change-Id: I420f43d1b54638883af0b8df6ccba2416c587868
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/292315
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
2 files changed