Pretty simple:
I have code using Object.getPrototypeOf(...) to get the inherited classes of a Dojo Widget (just a JS object). Object.getPrototypeO
Object.getPrototypeOf(...)
Object.getPrototypeO
Use https://github.com/kriskowal/es5-shim. Among other things, it supports Object.getPrototypeOf.
Source: ECMAScript 5 polyfills from Modernizr project