Add NumberKind to Slot struct.
Add NumberKind to Slot struct.

It is useful to know the type of data in a slot (float or int) if we
plan to show it in human-readable form.

Change-Id: I4befdfcca6826792cd09b6a06a71cfd639d55822
Bug: skia:12614
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/469076
Commit-Queue: John Stiles <f4fcf42d3bb5924557f1eeb3be66747535e585da@google.com>
Reviewed-by: Brian Osman <794c0b5534edf5601d88e1d41975d0262da12894@google.com>

aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,google/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,google/skia,google/skia,google/skia