Cleanup TODO in gen_tasks

It is well after December 2017

Bug: skia:
Change-Id: I3e48735dac9885606bdecab301379a1312966ff1
Reviewed-on: https://skia-review.googlesource.com/114361
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
2 files changed