Function update

external/.scrollLibs.js:6495–6498

(line, text, spans)

      return markedSpans ? markedSpans[n] : null
    }
    function update(line, text, spans) {
      updateLine(line, text, spans, estimateHeight$$1)
      signalLater(line, "change", line, change)
    }
    function linesFor(start, end) {
      var result = []
      for (var i = start; i < end; ++i) {