Invalid JS: Compiler emits invalid JS when throw followed by if or for

[epidemian]

This seemingly valid CS code:

throw if pedantic 
  new FatalError
else
  new ResumableError

Compiles to invalid JS:

throw if (pedantic) {
  new FatalError;
} else {
  new ResumableError;
};

I say seemingly valid because the same thing works for a function call:

raise = (e) -> throw e
raise if pedantic 
  new FatalError
else
  new ResumableError

var raise;

raise = function(e) {
  throw e;
};

raise(pedantic ? new FatalError : new ResumableError);

[bwin]

It also works if you add parentheses:

throw (if pedantic 
  new FatalError
else
  new ResumableError)

compiles to:

throw (pedantic ? new FatalError : new ResumableError);

[GeoffreyBooth]

Probably related, from #3357: The following compiles to invalid JS:

throw for v in list then v

Basically we shouldn’t allow if or for (or all expressions?) after throw.

[GeoffreyBooth]

Fixed by #4664.