Add support for get and set keywords

[1b8]

var obj = {
  get prop() {
    // ...
  },
  set prop(newProp) {
    // ...
  }
};

class Thing {
  get prop() {
    // ...
  }
  set prop(newProp) {
    // ...
  }
}

[Ben3eeE]

Seems like this issue has been fixed. I am not able to reproduce on latest master with either tree-sitter or textmate.