Robust shorthand parsing. Fixes #649

[tmcw]

This extends findTarget and the membership interference steps, treating ObjectProperty within
var-assigned objects the same as we did for ObjectMethods. It also adds tests that specifically test
findTarget directly.

Previously in a case like

var x = {
  /** add two numbers */
  add: function(x, y) { return x + y; },
  /** subtract two numbers
  subtract(x, y) { return x + y; }
};

The subtract method wouldn't be properly nested under the x object.

Fixes #649 and fixes #678