Empty item templates produces holes in collection

[kpdecker]

This can lead to future rendering failures when an inserted item's sibling can not be found.

  it('should work with empty elements', function() {
    var view = new Thorax.View({
      template: Handlebars.compile("{{#collection}}\n{{#if render}}\n{{letter}}\n{{/if}}\n{{/collection}}"),
      collection: new Thorax.Collection([
        {letter: 'a', render: false},
        {letter: 'b', render: true},
        {letter: 'c', render: false},
        {letter: 'd', render: true},
        {letter: 'e', render: true}
      ])
    });
    view.render();
    expect(view.$el.text()).to.equal('bde');
    expect(view.$('[data-model-cid]').length).to.equal(5);
  });

[kpdecker]

Under Handlebars 2.x this will fail with the following failure:

  1) collection should work with empty elements:
     Error: expected 3 to equal 5
      at Assertion.assert (thorax/node_modules/expect.js/index.js:96:13)
      at Assertion.be.Assertion.equal (thorax/node_modules/expect.js/index.js:216:10)
      at Context.<anonymous> (thorax/build/dev/test-fruit-loops-server.js:243:50)
      at Test.Runnable.run (thorax/node_modules/mocha/lib/runnable.js:221:32)
      at Runner.runTest (thorax/node_modules/mocha/lib/runner.js:374:10)
      at thorax/node_modules/mocha/lib/runner.js:452:12
      at next (thorax/node_modules/mocha/lib/runner.js:299:14)
      at thorax/node_modules/mocha/lib/runner.js:309:7
      at next (thorax/node_modules/mocha/lib/runner.js:247:23)
      at Object._onImmediate (thorax/node_modules/mocha/lib/runner.js:276:5)
      at processImmediate [as _immediateCallback] (timers.js:345:15)

[kpdecker]

cf8f488 masks this failure slightly due to the append only mode operation but we should output placeholder elements for empty content items so independent inserts will have the proper placeholders.