Implement portable variants of TypedArray.wrap

[jletellier]

Using e.g. Uint8Array.wrap(buffer) is valid code in AssemblyScript but doesn't work in regular TypeScript, so it isn't portable. As far as I can tell there needs to be a corresponding implementation in std/portable/index.js.

The following code snippet works for me:

Object.defineProperty(Uint8Array, "wrap", {
  value: function(buffer, byteOffset, length) {
    return new Uint8Array(buffer, byteOffset, length);
  }
});

Am I overlooking something or should I submit a pull request?

P.S. Thank you so much for this library!

[MaxGraey]

PR is welcomed) Good catch btw!

[MaxGraey]

Implemented in #1309