src/vs/editor/common/cursor/cursorMoveCommands.ts/CursorMoveCommands/_firstLineNumberInRange
class CursorMoveCommands:	private static _firstLineNumberInRange(model: ICursorSimpleModel, range: Range, count: number): number {
		let startLineNumber = range.startLineNumber;
		if (range.startColumn !== model.getLineMinColumn(startLineNumber)) {
			// Move on to the second line if the first line start is not included in the range
			startLineNumber++;
		}

		return Math.min(range.endLineNumber, startLineNumber + count - 1);
	}