Shopify/batman — pull request #610 by kristianpd (2012-12-07 01:26:54+00:00)
Title: Avoid unecessary property event creation

Applies similar refactoring to #608 to delay creating `PropertyEvent` instances until they are about to be written to.

Applies a small optimization to #608 to cache the ancestor event until we copy it locally (or never).

Overall this helps reduce object references more than anything with minor variances to CPU benchmarks

@hornairs @mattwdh @nciagra please