Fix gallery tracking

Chrome removed the prefix on transform, breaking the originalEvent property name check. Also, the analytics datalayer had been updated and broke the summaryTag tracking. Jshint ignore required because of underscored variable :/
That would test that the fixture is correct. I want to test that it takes what's in `fixture-incoming-slide` and copies the content into the actually gallery slide area here https://github.com/lonelyplanet/rizzo/pull/821/files#diff-3c44738950e015463af2bb904aebd1a5R6

`gallery.galleryTitle` is originally "A Sample Title", and this tests that it changes it to whatever is in the next slide (in this case "A new Caption")

You could write it out literally, but it tests the same thing. This way it means it won't break if someone updates the fixture content. 

Does that make sense or am I overlooking something?