Update 99_main_compiler.js

cli/tsc/99_main_compiler.js

@@ -8,9 +8,18 @@
 // that is created when Deno needs to type check TypeScript, and in some
 // instances convert TypeScript to JavaScript.
 
-// Removes the `__proto__` for security reasons.
+// Disables setting `__proto__` and emits a warning instead, for security reasons.
 // https://tc39.es/ecma262/#sec-get-object.prototype.__proto__
-delete Object.prototype.__proto__;
+Object.defineProperty(Object.prototype, '__proto__', {
+  configurable: true,
+  enumerable: false,
+  get () { return Object.getPrototypeOf(this) },
+  set (_) { 
+    console.warn(
+      "Prototype access via __proto__ attempted; __proto__ is not implemented in Deno due to security reasons. Use Object.setPrototypeOf instead."
+    )
+  }
+})
 
 ((window) => {
   /** @type {DenoCore} */