src/vs/editor/common/cursor/cursorMoveOperations.ts/MoveOperations/leftPosition
class MoveOperations:	public static leftPosition(model: ICursorSimpleModel, position: Position): Position {
		if (position.column > model.getLineMinColumn(position.lineNumber)) {
			return position.delta(undefined, -strings.prevCharLength(model.getLineContent(position.lineNumber), position.column - 1));
		} else if (position.lineNumber > 1) {
			const newLineNumber = position.lineNumber - 1;
			return new Position(newLineNumber, model.getLineMaxColumn(newLineNumber));
		} else {
			return position;
		}
	}