bug#73777: set-fontset-font doesn't set :size for specific characters when using some fonts

[Rodrigo Morales]

>  . did you reset use-default-font-for-symbols to nil? without that,
>    Emacs prefers to use the default face's font for punctuation and
>    symbols, effectively disregarding the fontsets

No. I didn't know that the variable use-default-font-for-symbols existed
when I wrote that message. Now that I know of its existence, I believe
that Emacs behaves consistently with regards to what I mentioned in my
first message.

>  . which fonts did you find problematic in this case? you say
>    "specific fonts", but it is not clear which fonts exhibit this
>    behavior

I thought that the font which was problematic was "Noto Sans Mono"
because when I used that font (in "Experiment 1" and "Experiment 2"), I
could not increase the size of the character “ (#x201C, LEFT DOUBLE
QUOTATION MARK) by evaluating (set-fontset-font t ?“ (font-spec :family
"Noto Sans Mono" :size 50)), . However, when I used "Fixed 5" (in
"Experiment 3"), evaluating (set-fontset-font t ?“ (font-spec :family
"Noto Sans Mono" :size 50)) did increase the size of the character
(#x201C, LEFT DOUBLE QUOTATION MARK).

Now that I know that the variable use-default-font-for-symbols controls
whether Emacs should honor fontsets, I don't think there's a problematic
font, instead it was my fault for not correctly knowing the variable
that instruct Emacs that it shoud honor fontsets.