code-dot-org/blockly — pull request #591 by Bjvanminnen (2014-05-19 23:36:17+00:00)
Title: [Finishes #71443508] stepping through while loop

Loops inject an extra "step" at the beginning that has a command of null and is used during code execution to check for infinite loops. While animating/stepping we want to ignore any of these, otherwise we have an extra step where we don't actually do anything.