convertToBlob farbling

[pilgrim-brave]

Chromium supports a non-standard extension to the offscreen canvas API called convertToBlob which could be used to get access to the unfarbled canvas contents. We should patch this API in the same way as toDataUrl and toBlob.

[bsclifton]

@pilgrim-brave any QA needed for this? If so, can you add steps here and label with QA/Yes. If not, can you share why (ex: covered by automated tests) and label with QA/No. Thanks! 😄

[rebron]

@LaurenWags I think we should stick with farbling. Maybe for relnotes: "Enhanced fingerprinting protection [or privacy?] by farbling convertToBlob