src/vs/editor/common/viewLayout/linesLayout.ts/LinesLayout/onLinesInserted
class LinesLayout:	public onLinesInserted(fromLineNumber: number, toLineNumber: number): void {
		this._checkPendingChanges();
		fromLineNumber = fromLineNumber | 0;
		toLineNumber = toLineNumber | 0;

		this._lineCount += (toLineNumber - fromLineNumber + 1);
		for (let i = 0, len = this._arr.length; i < len; i++) {
			const afterLineNumber = this._arr[i].afterLineNumber;

			if (fromLineNumber <= afterLineNumber) {
				this._arr[i].afterLineNumber += (toLineNumber - fromLineNumber + 1);
			}
		}
	}