Fix folding ranges for nested switch statements

[hopehadfield]

Fixes redhat-developer/vscode-java#2751

Normal (not collapsed):

Before fix:

After fix:

[rgrunber]

test this please.

[rgrunber]

Also, this isn't related to your change, but for the block regarding // Start & end overlap, adjust the previous one for visibility:, I would add a comment explaining it handles specifically try/catch if/else if where the curly brace that ends one expression is on the same line as the start of the other expression, where both are candidates to be folded.

Update: I mean it may become related to your change as I assume you'll have to update that block to deal with an annoying overlap :)

[rgrunber]

retest this please.

[rgrunber]

Change looks good to me. I was a bit iffy on ignoring the curly braces within the case statement, but we did that even before, so we may as well continue the practice since it also makes it simpler.

Reversing the candidate mapping also makes sense given that the starting line of a folding range is unique, and not the ending line (folding ranges could end on the same line).