Replace delete statements with variable = false;

There are a few articles and podcasts from Lars and Kasper who have said using delete is "dog slow" in class structures. "When you use delete V8 has to transform your object from a highly-optimized class structure into a slower hash table." (Apr 2012)

Does it make sense to remove the two delete statements from Base.js?

http://kendsnyder.com/posts/chrome-v8-creators-with-and-delete-are-dog-slow

http://coding.smashingmagazine.com/2012/11/05/writing-fast-memory-efficient-javascript/

http://perfectionkills.com/understanding-delete/