This totally overhauls the implementation to use ordinary inheritance-based type erasure. I give up for now getting my manual vtable shenanigans to work with MSVC. Still those same "expected ; before ), also expected ) before ;" errors.
I added support for uninitialized SkFunctions and operator=(), because it was fairly straightforward with this implementation.
The main downside here is that I've removed the inline implementation. All SkFunctions involve a heap allocation, even when just wrapping function pointers.
BUG=skia:
Review URL: https://codereview.chromium.org/1056673002
Let's start with baby steps in case some bot can't handle this.
I have left many TODOs, most of which I know how to do if this
looks feasible and useful.
BUG=skia:
Review URL: https://codereview.chromium.org/1049223003
