Remove old TW_DISABLE_PLAIN_TEXT_LOADER hack

src/extension-support/tw-load-script-as-plain-text.js

@@ -3,10 +3,6 @@
 const SingleEntryPlugin = require('webpack/lib/SingleEntryPlugin');
 
 module.exports.pitch = function (request) {
-    // Temporary hack to allow TW Desktop to avoid nonsensical errors
-    if (process.env.TW_DISABLE_PLAIN_TEXT_LOADER) {
-        return 'throw new Error("Loader was disabled at build time");';
-    }
     // Technically this loader does work in other environments, but our use case does not want that.
     if (this.target !== 'web') {
         return 'throw new Error("Not supported in non-web environment");';