[utils] Update isPlainObject implementation

This update adds support for checking plain object in non-v8/standard
runtimes as well (ie vercel edge-runtime)

Closes #36574 #39338

packages/mui-utils/src/deepmerge.ts

@@ -1,5 +1,23 @@
+function isObjectLike(value: unknown): value is Record<keyof any, unknown> {
+  return value != null && typeof value === 'object';
+}
+
+function getPrototypeOf(arg: unknown) {
+  return Object.getPrototypeOf(Object(arg));
+}
+
+const hasOwnProperty = Object.prototype.hasOwnProperty;
+
 export function isPlainObject(item: unknown): item is Record<keyof any, unknown> {
-  return item !== null && typeof item === 'object' && item.constructor === Object;
+  if (!isObjectLike(item)) {
+    return false;
+  }
+  const proto = getPrototypeOf(item);
+  if (proto === null) {
+    return true;
+  }
+  const Ctor = hasOwnProperty.call(proto, 'constructor') && proto.constructor;
+  return typeof Ctor === 'function' && Ctor instanceof Ctor;
 }
 
 export interface DeepmergeOptions {