anchor.diff:      | EOF
       | {this.lineTerminatorAhead()}?
       | {this.closeBrace()}?
  -    ;+    ;
  
positive.code:     | tryStatement
      | debuggerStatement
      | functionDeclaration
      | classDeclaration
      ;
  
  block
  
negative.code:     : block
      | variableStatement
      | emptyStatement
      | classDeclaration
      | expressionStatement
      | ifStatement
      | iterationStatement
  