At the moment we only support deep-copied ArrayBuffer serialised as QByteArray. #1326 needs a way of temporarily referencing a TypedArray or DataView from V8 without doing two unnecessary copies of the RGBA pixel data. (Once calling ArrayBuffer.slice to get pixel data out of a WebAssembly memory, and again doing a deep copy while serialising to QByteArray)

Canvases specifically only need Uint8ClampedArray, but having the whole family of TypedArray types will be helpful for future stuff like scriptable PCM audio.