[skottie] Remove defensive seek(0) from Animation ctor

It potentially causes unnecessary image frame loads.

Well-behaved clients should always seek() before calling render().

Bug: skia:9686
Change-Id: If16257dc947941541d9ae8906b5ec7b1754dd7df
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/257625
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
2 files changed