Porting to 2.8

Bug is #24015

Since we don't need this fix in master ASAP, let's get some test cases / asserts added to this PR. I'm running manual VS tests in the 2.8 port branch

I added a test case and an assert that immediately catches the problem (1) in compilation (2) in fourslash (3) in interactive VS Code usage, so I think this is ready to go.

Looks good. Can you add another fourslash test for the other repro we got?

@RyanCavanaugh can you send me the other minified repro? Since we didn't change the definition of getJSInitializerSymbol, and the binder code that creates symbols based on getJSInitializer is a single code path, I don't think it will prove anything new, but the cost of adding a second test is low.

Note that without the fix the assert fires for existing tests too: to wit, the ones that had changed baselines.

The two repros I have are

// file1.js
blah.prototype = {
    m: "q"
};

// file2.d.ts
declare class blah { }

and

// file1.js
var N = {};
N.X = function() { };

// file2.d.ts
declare namespace N {
    class X { }
}