=== tests/cases/compiler/propagationOfPromiseInitialization.ts ===
interface IPromise<T> {
>IPromise : IPromise<T>
>T : T

    then<TResult>(successCallback: (promiseValue: T) => TResult, errorCallback?: (reason: any) => TResult): IPromise<TResult>;
>then : <TResult>(successCallback: (promiseValue: T) => TResult, errorCallback?: (reason: any) => TResult) => IPromise<TResult>
>TResult : TResult
>successCallback : (promiseValue: T) => TResult
>promiseValue : T
>T : T
>TResult : TResult
>errorCallback : (reason: any) => TResult
>reason : any
>TResult : TResult
>IPromise : IPromise<T>
>TResult : TResult
}

var foo: IPromise<number>;
>foo : IPromise<number>
>IPromise : IPromise<T>

foo.then((x) => {
>foo.then((x) => {    // x is inferred to be a number    return "asdf";}).then((x) => {    // x is inferred to be string    x.length;    return 123;}) : IPromise<number>
>foo.then((x) => {    // x is inferred to be a number    return "asdf";}).then : <TResult>(successCallback: (promiseValue: string) => TResult, errorCallback?: (reason: any) => TResult) => IPromise<TResult>
>foo.then((x) => {    // x is inferred to be a number    return "asdf";}) : IPromise<string>
>foo.then : <TResult>(successCallback: (promiseValue: number) => TResult, errorCallback?: (reason: any) => TResult) => IPromise<TResult>
>foo : IPromise<number>
>then : <TResult>(successCallback: (promiseValue: number) => TResult, errorCallback?: (reason: any) => TResult) => IPromise<TResult>
>(x) => {    // x is inferred to be a number    return "asdf";} : (x: number) => string
>x : number

    // x is inferred to be a number
    return "asdf";
>"asdf" : string

}).then((x) => {
>then : <TResult>(successCallback: (promiseValue: string) => TResult, errorCallback?: (reason: any) => TResult) => IPromise<TResult>
>(x) => {    // x is inferred to be string    x.length;    return 123;} : (x: string) => number
>x : string

    // x is inferred to be string
    x.length;
>x.length : number
>x : string
>length : number

    return 123;
>123 : number

});