chunk navigation a problem for newline edge case

[mlilback]

$$
	\begin
{aligned}
	\dot{x} & = \sigma(y-x) \\
	\dot{y} & = \rho x - y -xz \\
	\dot{z} & = -\beta z + xy
	\end{aligned}
$$

```{r bar}
plot(rnorm(40))

• point r 2+2 $\frac{1}{n} \sum_{i=i}^{n} x_{i}$

chunk 3 is the newline between $$ and \'''. chunk 4 is bar. when trying to go to next/previous chunk, it will never move. 

SyntaxParser.chunksForRange used to use range.location-1, not having this problem, but having other problems.