Hello.  I've noticed that the regexp of Info-mode-font-lock-keywords
throws some false negatives and positives.

In latest Emacs, do these steps to see the bug.
1) Start Emacs: emacs -Q
2) Go to the Emacs Manual: C-h r
3) Go to the Basic node: m Basic RET
4) Go to the Inserting Text section: 1
5) Search for "which is": C-s which is RET
6) Type: M-x describe-text-properties
Notice that face is Info-quoted, even though point is not in a quote.

This is a false positive.  Under the same section, there's another false
positive: "To see which characters have " is quoted too.

Now to show a false negative, in the same Emacs Manual:
Search for this string C-s ‘’’.  That is: C-x 8 [ followed by C-x 8 ]
followed by C-x 8 ].
The search should get you to the Text Display section.  Move point to
the middle ’, the one that is being quoted, and again type:
M-x describe-text-properties.  It doesn't have the face Info-quoted,
even though it is a quote.

I hope I've described well enough the issue.  Proposed patch to follow.

Best regards,
Mauro.

In GNU Emacs 27.0.50 (build 3, i686-pc-linux-gnu, GTK+ Version 3.18.9)
 of 2019-04-08 built on the-blackbeard
Repository revision: 36dc39bfbf1a307769bd62dbe1311a1935737b51
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