Currently Promise has a custom constructor and it returns JavaScript Object instead of Promise wrapper object.
So because of this, Promise type is written as any type in IDL files (such as ImageBitmapFactories.idl).

To represent that we don't intend to use any type, we add `typedef any PromiseValue` and use |PromiseValue| instead.

When Promise wrapper object is introduced, these `typedef`s are removed and |PromiseValue| is replaced with |Promise|.

BUG=266700

Review URL: https://chromiumcodereview.appspot.com/22440006

git-svn-id: svn://svn.chromium.org/blink/trunk@156273 bbb929c8-8fbe-4397-9dbb-9b2b20218538