[skottie] Reduce CompositionBuilder stack footprint
[skottie] Reduce CompositionBuilder stack footprint

LayerBuilder has grown to be pretty chunky.  Using inline storage
SkSTArray<64> in stack-allocated CompositionBuilders is excessive
(and unnecessary).

-fstack-usage before:
  AnimationBuilder::attachPrecompLayer() 7536

-fstack-usage after:
  AnimationBuilder::attachPrecompLayer() 368


Change-Id: Ia905d58e02519d9251620f3eeedbbdc434e3392d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/319342
Reviewed-by: Mike Klein <14574f09dfa9b4e14759b88c3426a495a0e627b0@google.com>
Reviewed-by: Ben Wagner <53965154ffeecc4a10886eab9259e95965f2979a@google.com>
Commit-Queue: Florin Malita <a8262bf13ea8c26821e91ea9bca6740a77c96dcd@google.com>
Commit-Queue: Florin Malita <a8262bf13ea8c26821e91ea9bca6740a77c96dcd@chromium.org>

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