when using eclipse webtools JSDT, the validator doesn't recognise the "get someval() { return this.someVal }" syntax

Question

When using JSDT to edit a javascript source file using this syntax for getter and setter like so;

  get action() { return this.aAction },
  set action(action) { this.aAction = action },

it fails and returns an error;

Syntax error on token "get", : expected after this token

here is the full source example; http://pastebin.com/Xsfnk3b7

any suggestions on a work-around?

Is there some way to define "get" and "set" keywords...?