SkSL DSL code is now automatically incorporated into the output

Previously, a manual codeAppend call was required to add a statement. We
now automatically invoke codeAppend when a statement is destroyed.

Change-Id: I09eaf230b1d58242c3ff6abb85e970ed5ed3bce2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/371141
Auto-Submit: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
6 files changed