What is evolutionary computation? Is it a method of reinforcement learning? Or a separate method of machine learning? Or maybe none?
Please, cite references used to answer this question.
There are evolutionary methods that are explicitly aimed at solving the reinforcement learning problem. The subfield typically goes by the name of Learning Classifier Systems (LCS) or occasionally Genetics-Based Machine Learning (GBML).
Aside from that, I'm not sure your question has a very well-defined answer. It basically boils down to "what is machine learning?" There's no canon that we've all agreed on for how to answer that question. For some, EC might be a part of that subfield. For others, it isn't. I just sampled a handful of ML textbooks from my shelf, and about half contained material on evolutionary methods. I suspect 15 years ago that fraction would have been higher, but fashions change, and machine learning is very nearly a subfield of statistics now. EC methods don't fit that mold very well.