Symbol defines properties on Object prototype

[hotforfeature]

The Symbol polyfill defines all Symbols on the object prototype, which causes unexpected results.

// returns true with polyfill.io using features=Symbol.iterator, should be false
console.log(Symbol.iterator in {}); 

Angular checks for the present on the Symbol.iterator property instead of a non-undefined value when running change detection, which breaks when using polyfill.io.