To fix  crbug.com/701457 , we need multiple partial interfaces of WindowOrWorkerGlobalScope implemented as different classes in different modules. The binding relations are similar to this:

* In Window.idl:
Window implements WindowOrWorkerGlobalScope;

* In WorkerGlobalScope.idl:
WorkerGlobalScope implements WindowOrWorkerGlobalScope

* In modules/module1/WindowOrWorkerGlobalScopeModule1.idl:
[ImplementedAs=Module1
] partial interface WindowOrWorkerGlobalScope {
...};

* In modules/module2/WindowOrWorkerGlobalScopeModule2.idl:
[ImplementedAs=Module2
] partial interface WindowOrWorkerGlobalScope {
...};

etc. This seems to be an edge case which is not supported by the current binding engine.