database module typescript definition: update signature is wrong

[phra]

Hi,

there is a bug in the new database typescript definitions.

https://github.com/angular/angularfire2/blob/master/src/database/list/create-reference.ts#L11
i think that line no. 6 should be:

update: createDataOperationMethod<Partial<T>>(query.ref, 'update'),

otherwise the non destructive .update() wants as second arguments a complete T object instead of a Partial.

[phra]

as a workaround you can double cast the payload as { payload: 'payload' } as any as T in strict environments.