Backwards Incompatible Changes

• The debug loader no longer downlevels sources in the browser. The alternative recommendation is to use a downleveling development server instead. (468188f4dc0d6fd756a142f2c7b72777fc0ebcb4)
• transpile.js has been deleted (55bb681f14bc33227567a605fd6bb1f6ece28a98)
• Remove configurability for whether window.open with noreferrer implies noopener (3e83d9679478fde7a2e2aa05f3aabb83abefb1e3)

Other Changes

• Closure editor: fix a rare case where extra strings were inserted when a list was removed (e69cdb6acdf19ea145a7df40b99340e75b937a4b)