Declare RouteConfig.navModel for TypeScript projects

[heruan]

I'm porting my projects to TypeScript, and I was used to dynamically set the page title in the activate function:

activate(params, routeConfig, navigationInstruction) {
    routeConfig.navModel.setTitle("My Title");
    // This is simplified, the title will be set after retrieving server side info
}

but using TypeScript I've found the RouteConfig.navModel property isn't declared and the compiler complains:

Property 'navModel' does not exist on type 'RouteConfig'.

[jwahyoung]

@heruan Thank you for the contribution. I can verify that the property exists in the ES2016 skeleton. The Typescript definition files are generated from the codebase itself, so feel free to submit a pull request with the necessary file changes for this fix.

@EisenbergEffect This may need the bug tag.