Mark cached as a MethodDecorator instead of PropertyDecorator

[boris-petrov]

I believe that's more correct as cached uses/needs descriptor which is only available in MethodDecorator.

cc @dfreeman, @chriskrycho, @jamescdavis, @wagenet

Sorry for pinging so many people but I'm not sure who I should. 😄 Is there like a TypeScript team that I can mention?

[kategengler]

@emberjs/typescript-core ^

[gitKrystan]

I've run into this also. Pinging the rest of the TS team to see if there's a reason it was typed as PropertyDecorator in the first place.

[chriskrycho]

As you can see here at the implementation, it is… not well-typed, and I think the use of PropertyDecorator was basically just someone’s guess at the right thing at some point, which has stuck around. 😂 On digging back through the relevant TS docs, I think this should actually be an accessor decorator (see here specifically), and as far as I can tell the only corresponding type TS supplies is indeed MethodDecorator, so this seems like the right move. 👍🏼

[kategengler]

Thank you!