lineAt

Get the document line at pos.

Note: unlike CodeMirror's lineAt, this returns the real doc Line for source compatibility with callers that rely on line metadata (Line.to, Line.number, etc.). It therefore cannot represent the portion of a line produced by a simulated break. The bias parameter is accepted for API parity but does not split the returned Line; textAfterPos, column and lineIndent honor the simulated break via the private lineContentAt helper instead.