Extend getNonStdFontMap for non-embedded version of the ItcSymbol font (issue 11532)

Despite its name, the fonts in ItcSymbol-family are "regular" fonts and not Symbol ones. However, given that the font name contains the word "Symbol" we ended up picking the wrong code-path in the `Font.fallbackToSystemFont`-method.

*Please note:* While this patch ensures that the text becomes readable, by falling back a standard font, the rendering will obviously not be perfect. However, that's the PDF generators "fault" since non-embedded fonts cannot be guaranteed to render correctly in all environments.

Author: Snuffleupagus

src/core/standard_fonts.js

@@ -129,6 +129,12 @@ const getNonStdFontMap = getLookupTableFactory(function (t) {
   t["ComicSansMS-Bold"] = "Comic Sans MS-Bold";
   t["ComicSansMS-BoldItalic"] = "Comic Sans MS-BoldItalic";
   t["ComicSansMS-Italic"] = "Comic Sans MS-Italic";
+  t["ItcSymbol-Bold"] = "Helvetica-Bold";
+  t["ItcSymbol-BoldItalic"] = "Helvetica-BoldOblique";
+  t["ItcSymbol-Book"] = "Helvetica";
+  t["ItcSymbol-BookItalic"] = "Helvetica-Oblique";
+  t["ItcSymbol-Medium"] = "Helvetica";
+  t["ItcSymbol-MediumItalic"] = "Helvetica-Oblique";
   t.LucidaConsole = "Courier";
   t["LucidaConsole-Bold"] = "Courier-Bold";
   t["LucidaConsole-BoldItalic"] = "Courier-BoldOblique";

test/pdfs/issue11532.pdf.link

@@ -0,0 +1 @@
+https://github.com/mozilla/pdf.js/files/7086733/ar99.pdf

test/test_manifest.json

@@ -76,6 +76,15 @@
        "link": false,
        "type": "eq"
     },
+    {  "id": "issue11532",
+       "file": "pdfs/issue11532.pdf",
+       "md5": "9216481d259ae2b8d747236e745cbc80",
+       "rounds": 1,
+       "link": true,
+       "firstPage": 2,
+       "lastPage": 2,
+       "type": "eq"
+    },
     {  "id": "issue11549",
        "file": "pdfs/issue11549_reduced.pdf",
        "md5": "a1ea636f413e02e10dbdf379ab4a99ae",