Delete copyTo(Allocator), hide copyTo() behind flag

Replace uses of copyTo() in Skia.

Bug: skia:6464
Change-Id: I921dc53a1c29a5176d18f05741f7c0b5a008e548
Reviewed-on: https://skia-review.googlesource.com/14502
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Mike Reed <reed@google.com>
30 files changed