Try optional catch binding

[tuchida]

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/try...catch#the_exception_identifier

  try {
    JSON.parse(text);
    return true;
  } catch {
    return false;
  }

The omission of the exception value is implemented, but there are another error. ref. #915
We need to either fix #915 or ignore VerifyError.

Closes #965

[tuchida]

@gbrail @p-bakker Could you review it? Or should I wait for the problem to be fixed on Android?

[p-bakker]

This still holds true?

[tuchida]

1b473d6 I fixed.

[p-bakker]

Not sure if the Android thing should hold this PR (and others) back.

Left you one little comment, most of the changes are beyond me unfortunately

[tuchida]

Thank you for your comment. I'll wait for a while.

[gbrail]

This works great. I'm going to squash some commits and push manually. Thanks!