labeled block support

[SheetJSDev]

The following example is from MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/label#using_a_labeled_block_with_break

You can use labels within simple blocks, but only break statements can make use of non-loop labels.

foo: {
  console.log('face');
  break foo;
  console.log('this will not be executed');
}
console.log('swap');

// this will log:

// "face"
// "swap"

Saving that to a file and testing with cargo run -- test.js prints the error

Uncaught "SyntaxError": "Cannot use the undeclared label 'foo'"

[meirochun]

Looks like this bug already in execution since Feb 23. #1852
And it was already expected, it's on PR's describe.

[Razican]

This might be related to the fact that we don't use completion records. We only check for labels on loops, afaik, instead of on "any labeled statement", which should be the case. But we also don't have the notion of a "labeled statement" I think.