src/vs/editor/browser/view/viewLayer.ts/RenderedLinesCollection/onLinesChanged
class RenderedLinesCollection:	public onLinesChanged(changeFromLineNumber: number, changeCount: number): boolean {
		const changeToLineNumber = changeFromLineNumber + changeCount - 1;
		if (this.getCount() === 0) {
			// no lines
			return false;
		}

		const startLineNumber = this.getStartLineNumber();
		const endLineNumber = this.getEndLineNumber();

		let someoneNotified = false;

		for (let changedLineNumber = changeFromLineNumber; changedLineNumber <= changeToLineNumber; changedLineNumber++) {
			if (changedLineNumber >= startLineNumber && changedLineNumber <= endLineNumber) {
				// Notify the line
				this._lines[changedLineNumber - this._rendLineNumberStart].onContentChanged();
				someoneNotified = true;
			}
		}

		return someoneNotified;
	}