[dart2js] Problems with statement labels in generated code

[rakudrama]

• Labels from inlined functions collide with each other and labels from the inlining host [dart2js] Label name collisions when inlining labeled statements #51652
• Generated code contains useless labels that could be removed (see the generated code in [dart2js] Label name collisions when inlining labeled statements #51652)
• Label names are not minified.

[rakudrama]

Example useless label, where the label and break statements could be removed

      else {
        base = A._Parser_toType(t1, parser.e, head);
        $label0$0:
          if (12 === base._kind) {
            stack.push(A._Universe__lookupGenericFunctionRti(t1, base, $arguments, parser.n));
            break $label0$0;
          } else {
            stack.push(A._Universe__lookupBindingRti(t1, base, $arguments));
            break $label0$0;
          }
      }