findBlockScoped(name) {
    if (this.vars[name]) {
      return [];
    }
    if (this.parent) {
      return this.parent.findBlockScoped(name);
    }
    return [];
  }
Looks up variables from block scope.
(i.e. the parent block scope of the function scope.)

When variable found from function scope instead,
returns an empty array to signify it's not properly block-scoped.

@param  {String} name Variable name
@return {Variable[]} The found variables (empty array if none found)