match spec re: FastTextEncoder

text.js

@@ -28,15 +28,15 @@ if (scope['TextEncoder'] && scope['TextDecoder']) {
   return false;
 }
 
+// used for FastTextDecoder
+const validUtfLabels = ['utf-8', 'utf8', 'unicode-1-1-utf-8'];
+
 /**
  * @constructor
- * @param {string=} utfLabel
  */
-function FastTextEncoder(utfLabel='utf-8') {
-  if (utfLabel !== 'utf-8' && utfLabel !== 'utf8') {
-    throw new RangeError(
-      `Failed to construct 'TextEncoder': The encoding label provided ('${utfLabel}') is invalid.`);
-  }
+function FastTextEncoder() {
+  // This does not accept an encoding, and always uses UTF-8:
+  //   https://www.w3.org/TR/encoding/#dom-textencoder
 }
 
 Object.defineProperty(FastTextEncoder.prototype, 'encoding', {value: 'utf-8'});
@@ -116,7 +116,7 @@ FastTextEncoder.prototype.encode = function(string, options={stream: false}) {
  * @param {{fatal: boolean}=} options
  */
 function FastTextDecoder(utfLabel='utf-8', options={fatal: false}) {
-  if (utfLabel !== 'utf-8' && utfLabel !== 'utf8') {
+  if (validUtfLabels.indexOf(utfLabel.toLowerCase()) == -1) {
     throw new RangeError(
       `Failed to construct 'TextDecoder': The encoding label provided ('${utfLabel}') is invalid.`);
   }