Ongoing sync:ing of some default metadata based on the feedback of users on various platforms (b=21392,120198)

layout/mathml/base/src/mathfont.properties

@@ -33,7 +33,7 @@ mathfont_missing_dialog_message = To properly display the MathML on this page yo
 # See the documentation at the end of this file for details on the setup of
 # the property file associated to each font. This order can be overriden by
 # setting the pref("font.mathfont-family", "CMSY10, CMEX10, ...") or by
-# setting the font-family list in :-moz-math-font-style-stretchy in mathml.css.
+# setting the font-family list in :-moz-math-stretchy in mathml.css.
 
 font.mathfont-family = CMSY10, CMEX10, Math1, Math2, Math4, MT Extra, Symbol
 
@@ -74,13 +74,15 @@ mathvariant.double-struck = \uEF8C\uEF8D\u2102\uEF8E\uEF8F\uEF90\uEF91\u210D\uEF
 # the comma-separated list of fonts like in the font-family property of CSS.
 # A character can request different fonts for its variants and for its parts.
 
-# Use the safer Symbol font for ≤ And also for ≥ for the sake of uniformity
+# Use the safer Symbol font for some chars (≤ ≥ etc)
 # @see http://bugzilla.mozilla.org/show_bug.cgi?id=120198#c27
 # Note: setting base fonts for non-stretchy characters only works
 # for operators that are ultimately handled by nsMathMLChar.
 # @see how |useMathMLChar| is set in nsMathMLmoFrame::Stretch() & Paint().
+# Override with: pref("font.mathfont-family.\\u2264.base", "CMSY10, etc")
 font.mathfont-family.\u2264.base     = Symbol
 font.mathfont-family.\u2265.base     = Symbol
+font.mathfont-family.\u2212.base     = Symbol
 
 # CMSY10 or Math2 are preferred for Sqrt at its base size
 font.mathfont-family.\u221A.base     = CMSY10, Math2
@@ -459,6 +461,7 @@ operator.\u21AA.infix = stretchy:horizontal lspace:thickmathspace rspace:thickma
 operator.\u23B0.prefix = stretchy:vertical fence:true lspace:0em rspace:0em # ⎰ ⎰
 operator.\u23B1.postfix = stretchy:vertical fence:true lspace:0em rspace:0em # ⎱ ⎱
 operator.\u22C5.infix = lspace:thinmathspace rspace:thinmathspace # ċ
+operator.\u2282.infix = lspace:thickmathspace rspace:thickmathspace # ⊂
 
 
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