Fix an issue in `registerForNg1Tests`, where it passes a `null` as `ng1Injector` to `_bootstrapDone`. This causes a "TypeError: Cannot read property 'get' of null" to be thrown from `_bootstrapDone`.
Fix an issue in `registerForNg1Tests`, where it passes a `null` as `ng1Injector` to `_bootstrapDone`. This causes a "TypeError: Cannot read property 'get' of null" to be thrown from `_bootstrapDone`.