Allow new Blob() to accept Uint8Array directly

[lianghai]

Often an Uint8Array is already available. For example, Node.js Buffer is compatible with Uint8Array, and .bytes() has also been recently added to the Response API in addition to .arrayBuffer() (see also the background discussion).

Converting an Uint8Array to an ArrayBuffer can also be error-prone because of the sharing of an underlying ArrayBuffer (I just got bitten by this in the Unicode core spec’s codebase…). For example, instead of:

const arrayBuffer = readFileSync(path).buffer;

One must remember to do:

const buffer = readFileSync(path);
const arrayBuffer = buffer.buffer.slice(
  buffer.byteOffset,
  buffer.byteOffset + buffer.byteLength,
);

This PR also fixes the type error at:

harfbuzzjs/examples/harfbuzz.example.node.js

Line 9 in bced90b

var blob = new Blob(fs.readFileSync(fontPath));

[khaledhosny]

Thanks!