Removed a number of utility methods from DSLWriter

DSLWriter is about to be renamed to something non-DSL-specific, and
(especially since we're in the middle of trying to break up some of our
big classes anyway) it didn't feel right to leave a pile of extremely
DSL-specific utility methods in it. And since it turns out that none of
these methods really do much of anything anymore, it seemed best to
just kill them all.

Change-Id: I5e257f87108a7a6db7fc1c01bab4e6c1544d60b0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/455158
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
12 files changed