Move symbolic font glyphs to private use area if they don't have unic…

…ode mappings.

src/core/fonts.js

@@ -922,7 +922,9 @@ var Font = (function FontClosure() {
       var fontCharCode = originalCharCode;
       // First try to map the value to a unicode position if a non identity map
       // was created.
+      var hasUnicodeValue = false;
       if (!isIdentityUnicode && toUnicode.has(originalCharCode)) {
+        hasUnicodeValue = true;
         var unicode = toUnicode.get(fontCharCode);
         // TODO: Try to map ligatures to the correct spot.
         if (unicode.length === 1) {
@@ -937,7 +939,7 @@ var Font = (function FontClosure() {
       // with firefox and thuluthfont).
       if ((usedFontCharCodes[fontCharCode] !== undefined ||
            isProblematicUnicodeLocation(fontCharCode) ||
-           (isSymbolic && isIdentityUnicode)) &&
+           (isSymbolic && (isIdentityUnicode || !hasUnicodeValue))) &&
           nextAvailableFontCharCode <= PRIVATE_USE_OFFSET_END) { // Room left.
         // Loop to try and find a free spot in the private use area.
         do {