Fix general bug with the constructor registry

Since 9260316 jsdom has not worked, seemingly due to some weird interaction between Symbol.for and VM context objects. This seems to fix things, and it's not clear why we used a cross-realm symbol for this anyway.

Author: domenic

lib/output/utils.js

@@ -29,7 +29,7 @@ function newObjectInRealm(globalObject, object) {
 const wrapperSymbol = Symbol("wrapper");
 const implSymbol = Symbol("impl");
 const sameObjectCaches = Symbol("SameObject caches");
-const ctorRegistrySymbol = Symbol.for("[webidl2js]  constructor registry");
+const ctorRegistrySymbol = Symbol("[webidl2js] constructor registry");
 
 const AsyncIteratorPrototype = Object.getPrototypeOf(Object.getPrototypeOf(async function* () {}).prototype);