skia: add bitmap color table support
skia: add bitmap color table support

Fix 2/4/8 bits per pixel bitmaps
that PDFium transposes into 8 bpp
indexed.

R=tsepez@chromium.org,dsinclair@chromium.org,reed@google.com

Review-Url: https://codereview.chromium.org/2011153002

DrAlexx/pdfium,DrAlexx/pdfium,DrAlexx/pdfium,DrAlexx/pdfium