Fix(49702): LS crash in binder for module in a JS file

[navya9singh]

Fixes #49702
Crash occurs due to unexpected module in a .js file. Adding a case in bindThisPropertyAssignment() to handle a ModuleDeclaration fixes the problem.

[sandersn]

Couple of small requests:

• add a comment
• clean up test

[sandersn]

This is part of the .js emit for the thisKeyword test and shouldn't be part of the test case.

[sandersn]

remove this line, because it hides the fact that this test is in a .js file.

[DanielRosenwasser]

Move the filename comment closer to the actual code. Then add another section with // @filename: b.js that has similar same code but uses a namespace declaration:

// @filename: b.js
namespace blah {
    this.prop = 42;
}

Also, rename the containing file to thisAssignmentInNamespaceDeclaration1.ts.

Naming the test after the original behavior ("crash") is not really helpful long-term. Just name them after what's happening in the test, make sure we don't crash, and the baseline will demonstrate the actual behavior.

[sandersn]

@DanielRosenwasser do you want to take another look at this? Because I think it's ready to merge now.