moved SkSL FunctionReference/TypeReference data into IRNode

Change-Id: Ie3982e22c764455f3ae11472f6d1cacf4e9f64ba
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/325458
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
7 files changed