updateCodeBlockSelection was only ever called from the two AppKit
text-delegate callbacks (textDidChange / selection-changed), never
from the programmatic rebuildTextStorageAndStyle load path. Line
number gutters (and the built-in copy-code button) stayed empty on a
cold document open until the user's first click or keystroke.
Threads the rebuild's own parsed document into the same call instead
of leaving cachedCodeBlockTokens empty until the next real edit.
Puranjay Savar Mattas
3c3a5865bd