refactor(Router): replace outdated type checks with a null check
refactor(Router): replace outdated type checks with a null check

The type checks date back to a time when a route definition supported loading a
component both by type and factory. Now that only factories are supported, the
code is strongly typed, making this explicit check unnecessary.

PiperOrigin-RevId: 222880872

matanlurey/angular,angulardart/angular,matanlurey/angular,angulardart/angular,angulardart/angular,matanlurey/angular