Instantiate contextual types for return expressions

[ahejlsberg]

Fixes #32349.

[ahejlsberg]

@typescript-bot run dt
@typescript-bot test this

[typescript-bot]

Heya @ahejlsberg, I've started to run the parallelized Definitely Typed test suite on this PR at 6f637b0. You can monitor the build here. It should now contribute to this PR's status checks.

[typescript-bot]

Heya @ahejlsberg, I've started to run the extended test suite on this PR at 6f637b0. You can monitor the build here. It should now contribute to this PR's status checks.

[ahejlsberg]

DT test failures look like preexisting conditions unrelated to this PR.

RWC tests have one failure that boils down to this:

declare function foo<T>(x: T | Promise<T>): void;
declare let b: false | Promise<true>;
foo(b);  // Error

We fail to infer boolean for T, instead inferring just true. The issue is the way we give lower priority to direct inferences to naked type parameters in unions. I will think about ways to fix this.

[ahejlsberg]

Verified that there are no differences in RWC tests between this and the master branch.

[ahejlsberg]

So, now that #32460 is in and RWC is clean, I'm going to merge this.