#23377 updated the babel transforms to remove assert calls. This should have paved the way for the removal of AmpPass.java from the custom closure compiler runner. However, removing AmpPass.java increases the number of instances of assert in v0.js from 20 to 80.
Before removing AmpPass.java: 20 instances
After removing AmpPass.java: 80 instances
See discussion at #23377 (comment)