Replace remaining vector<Expression>s with ExpressionArray.

This fixes up a handful of places which weren't caught in the initial
work (at http://review.skia.org/325861) because they haven't been
converted to the new IRNode structure yet.

Change-Id: I86b61fe3c601711b5802fe35218ca2e6378634da
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/326357
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
6 files changed