Use Ruby's multiline string facility here.

```ruby
page.evaluate_script <<END_STR
$.getScript('https://raw.github.com/mattheworiordan/jquery.simulate.drag-sortable.js/master/jquery.simulate.drag-sortable.js', function () {
  $('[data-block-id=\"#{block_1a.id}\"]').simulateDragSortable({ move: 1 });
});
END_STR
```