fix: support cross-context Uint8Array in TextEncoder#encodeInto

Author: ChALkeR

fallback/encoding.js

@@ -55,6 +55,12 @@ function isAnyArrayBuffer(x) {
   return s === '[object ArrayBuffer]' || s === '[object SharedArrayBuffer]'
 }
 
+function isAnyUint8Array(x) {
+  if (x instanceof Uint8Array) return true
+  if (!x || !ArrayBuffer.isView(x) || x.BYTES_PER_ELEMENT !== 1) return false
+  return Object.prototype.toString.call(x) === '[object Uint8Array]'
+}
+
 const fromSource = (x) => {
   if (x instanceof Uint8Array) return x
   if (ArrayBuffer.isView(x)) return new Uint8Array(x.buffer, x.byteOffset, x.byteLength)
@@ -217,7 +223,7 @@ export class TextEncoder {
 
   encodeInto(str, target) {
     if (typeof str !== 'string') str = `${str}`
-    if (!(target instanceof Uint8Array)) throw new TypeError('Target must be an Uint8Array')
+    if (!isAnyUint8Array(target)) throw new TypeError('Target must be an Uint8Array')
     if (target.buffer.detached) return { read: 0, written: 0 } // Until https://github.com/whatwg/encoding/issues/324 is resolved
 
     const tlen = target.length