Merge perspective feature for PDF.

From Skia's repo:
Add SkPDFDeviceFlatenner which extends SkPDFDevice to add support
to flatten the path and the text when we have perspective. prepare
to deprecate SkPDFDevice constructor, and route gm and render_pdfs
to use SkDocument::Create pdf interface instead. - controlled by a
flag add comments where we are supposed to flatten other features
(paint, shaders, ... )
Implement perspective for bitmaps in pdf.
PDF: support perspective in simple shaders. (this version does not
work well with tilling)


Change-Id: I48ea88d231231215349f155d972c6b9e1e127c71
15 files changed