Quote on multiple lines (with inner apostrophe in math mode) causes issues

[jlelong]

Originally posted by @gertab in James-Yu/LaTeX-Workshop#3939

When quote (``...'') is split over multiple lines and there is an apostrophe in math mode, the text following it loses its coloring scheme.

No problem for versions up to 9.11.4. However in versions 9.11.5 and upwards, there is this issue.

The following snippet reproduces the issue, where the bottom text loses its color scheme:

\documentclass{article}

\begin{document}

Original text

``This $x'$ is 
on the same line''

Bottom text and math symbols $x$

\end{document}

From the given example both Original text and Bottom text and math symbols $x$ should be the same color.

[jlelong]

Related to #59

[gertab]

Thanks!