Clear non-image stuff out of SkImage.cpp

Change-Id: I3fd2378e25ae86b116be08edf31be07d2be802c6
Bug: skia:13983
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/648856
Reviewed-by: Nicolette Prevost <nicolettep@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Nicolette Prevost <nicolettep@google.com>
Auto-Submit: Kevin Lubick <kjlubick@google.com>
7 files changed