fix: don't expose `isolatedWorld` to global (#16208)

lib/isolated_renderer/init.js

@@ -2,8 +2,6 @@
 
 /* global nodeProcess, isolatedWorld */
 
-window.isolatedWorld = isolatedWorld
-
 // Note: Don't use "process", as it will be replaced by browserify's one.
 const v8Util = nodeProcess.atomBinding('v8_util')