Use approximate transcendental functions

These only rely on operations that are guaranteed to round
perfectly by IEEE, so the results are consistent across
all implementations.

Bug: skia:
Change-Id: I1bacd4ee8f5a3066f4fe76700ce23f9568073290
Reviewed-on: https://skia-review.googlesource.com/117084
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
21 files changed