Fix JS strict mode error in shell_minimal.js (#20226)

Author: steveanton

src/shell_minimal.js

@@ -172,7 +172,8 @@ var _scriptDir = (typeof document != 'undefined' && document.currentScript) ? do
 var ENVIRONMENT_IS_WORKER = typeof importScripts == 'function',
   ENVIRONMENT_IS_PTHREAD = ENVIRONMENT_IS_WORKER && !ENVIRONMENT_IS_WASM_WORKER;
 #else
-var ENVIRONMENT_IS_WORKER = ENVIRONMENT_IS_PTHREAD = typeof importScripts == 'function';
+var ENVIRONMENT_IS_WORKER = typeof importScripts == 'function',
+  ENVIRONMENT_IS_PTHREAD = ENVIRONMENT_IS_WORKER;
 #endif
 
 var currentScriptUrl = typeof _scriptDir != 'undefined' ? _scriptDir : ((typeof document != 'undefined' && document.currentScript) ? document.currentScript.src : undefined);