gif: override slice()

(cherry picked from commit 41532d2)

backport TextLayout types fix

Co-Authored-By: Hideo Hattori <hhatto.jp@gmail.com>

drawBox: floor components

api: support disposal modes

(cherry picked from commit 3f09bcf)

fix porting errors

fix gif decoding

(cherry picked from commit 5e7c88d)

fix getPixelAt

(cherry picked from commit c77881b)

fix text rendering wrap style

(cherry picked from commit 7fe0cdb)

update wasm

GIF encoder: free stream

(cherry picked from commit 4949e44)