Suggestion

In #9211: we are planning to enforce the following invariants in our AST for VariableDeclaration, specifically the declarators in declarations:

• definite can only be true if declare: false and kind: "let" | "var", so the following are all parsing errors:

  const x! = 1;
  declare let x!: string;

• If definite: true, then init: null, and the identifier has a type annotation:

  let x! = 1;
  let x!;

• If declare: true and kind: "let" | "var", then init: null:

  declare let x = 1;

• If declare: false and kind: "const" then init is non-null:

  const x;

@sosukesuzuki @fisker Do these look safe to you?