Merge pull request #12 from quamotion/fixes/optional-arguments

...e/ChromeDevTools/Protocol/Chrome/Runtime/EventListener.cs

...s/Protocol/Chrome/Runtime/ExecutionContextCreatedEvent.cs

...ls/Protocol/Chrome/Runtime/ExecutionContextDescription.cs

...Protocol/Chrome/Runtime/ExecutionContextDestroyedEvent.cs

.../Protocol/Chrome/Runtime/ExecutionContextsClearedEvent.cs

...Tools/Protocol/Chrome/Runtime/GetEventListenersCommand.cs

...eDevTools/Protocol/Chrome/Runtime/GetPropertiesCommand.cs

...s/Protocol/Chrome/Runtime/GetPropertiesCommandResponse.cs

...ols/Protocol/Chrome/Runtime/InternalPropertyDescriptor.cs

...e/ChromeDevTools/Protocol/Chrome/Runtime/ObjectPreview.cs

...omeDevTools/Protocol/Chrome/Runtime/PropertyDescriptor.cs

...ChromeDevTools/Protocol/Chrome/Runtime/PropertyPreview.cs

...ce/ChromeDevTools/Protocol/Chrome/Runtime/RemoteObject.cs

...Protocol/Chrome/ServiceWorker/DebugOnStartUpdatedEvent.cs

...ols/Protocol/Chrome/ServiceWorker/DispatchMessageEvent.cs

...rotocol/Chrome/ServiceWorker/ServiceWorkerRegistration.cs

...ols/Protocol/Chrome/ServiceWorker/ServiceWorkerVersion.cs

...Tools/Protocol/Chrome/ServiceWorker/WorkerCreatedEvent.cs

...Protocol/Chrome/ServiceWorker/WorkerErrorReportedEvent.cs

...ol/Chrome/ServiceWorker/WorkerRegistrationUpdatedEvent.cs