test: isolate hr-time specific wpt global init

PR-URL: #46795
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Michaël Zasso <[email protected]>

Author: panva

test/common/wpt.js

@@ -484,9 +484,7 @@ class WPTRunner {
   pretendGlobalThisAs(name) {
     switch (name) {
       case 'Window': {
-        this.globalThisInitScripts.push(
-          `global.Window = Object.getPrototypeOf(globalThis).constructor;
-          self.GLOBAL.isWorker = () => false;`);
+        this.globalThisInitScripts.push('globalThis.Window = Object.getPrototypeOf(globalThis).constructor;');
         this.loadLazyGlobals();
         break;
       }

test/wpt/test-hr-time.js

@@ -5,6 +5,9 @@ const { WPTRunner } = require('../common/wpt');
 
 const runner = new WPTRunner('hr-time');
 
+runner.setInitScript(`
+  self.GLOBAL.isWorker = () => false;
+`);
 runner.pretendGlobalThisAs('Window');
 
 runner.runJsTests();