Address Joey's feedback

build/conformance.textproto

@@ -333,3 +333,25 @@ requirement: {
     "See also https://bit.ly/3wAsoj5"
   whitelist_regexp: "node_modules/"
 }
+
+# Disallow the general use of TextDecoder and TextEncoder, which is not
+# available on all supported platforms.
+requirement: {
+  type: BANNED_NAME_CALL
+  value: "TextDecoder"
+  value: "window.TextDecoder"
+  error_message:
+    "Using \"TextDecoder\" directly is not allowed; "
+    "because is not supported on Xbox and old browsers."
+  whitelist_regexp: "lib/util/string_utils.js"
+}
+
+requirement: {
+  type: BANNED_NAME_CALL
+  value: "TextEncoder"
+  value: "window.TextEncoder"
+  error_message:
+    "Using \"TextEncoder\" directly is not allowed; "
+    "because is not supported on Xbox and old browsers."
+  whitelist_regexp: "lib/util/string_utils.js"
+}

demo/index.html

@@ -50,8 +50,6 @@
     <script defer src="../node_modules/tippy.js/umd/index.min.js"></script>
     <!-- Improved PWA capability on mobile Safari is enabled by loading pwacompat: -->
     <script defer src="../node_modules/pwacompat/pwacompat.min.js"></script>
-    <!-- TextDecoder polyfill, required for legacy Edge. -->
-    <script defer src="../node_modules/fastestsmallesttextencoderdecoder/EncoderDecoderTogether.min.js"></script>
 
     <!-- Include IMA SDK to enable client-side ad insertion: -->
     <script type="text/javascript" src="https://imasdk.googleapis.com/js/sdkloader/ima3.js"></script>

docs/tutorials/upgrade.md

@@ -25,6 +25,7 @@ application:
     - TextDecoder/TextEncoder platform support or polyfill required (affects
       Xbox One, but not evergreen browsers); we suggest the polyfill
       [https://github.com/anonyco/FastestSmallestTextEncoderDecoder](fastestsmallesttextencoderdecoder/EncoderDecoderTogether.min.js)
+      Fallback included by default in v4.2
 
   - Support removed:
     - IE11 support removed

package.json

@@ -27,7 +27,6 @@
     "eslint-config-google": "^0.14.0",
     "eslint-plugin-shaka-rules": "file:./build/eslint-plugin-shaka-rules",
     "esprima": "^4.0.1",
-    "fastestsmallesttextencoderdecoder": "^1.0.22",
     "fontfaceonload": "^1.0.2",
     "google-closure-compiler-java": "^20220301.0.0",
     "google-closure-deps": "https://gitpkg.now.sh/google/closure-library/closure-deps?d7736da6",