Update FunctionDeclaration to take 'is-builtin' from the Context.

We no longer need to explicitly pass this variable in since it lives in
the Context.

Change-Id: Ib8e753907578518e593cc3cd36f6f17871d95eec
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/455659
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
3 files changed