A couple of small String.fromCodePoint improvements (PR 11698 and 11769 follow-up)

- Add a reduced test-case for issue 11768, to prevent future regressions.
   (Given that PR 11769 is only a work-around, rather than a proper solution, it may not be entirely accurate for the issue to be closed as fixed.)

 - Add more validation of the charCode, as found by the heuristics, in `PartialEvaluator._buildSimpleFontToUnicode` to prevent future issues.

src/core/evaluator.js

@@ -2587,7 +2587,7 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
                 code = unicode;
               }
           }
-          if (code > 0 && Number.isInteger(code)) {
+          if (code > 0 && code <= 0x10ffff && Number.isInteger(code)) {
             // If `baseEncodingName` is one the predefined encodings, and `code`
             // equals `charcode`, using the glyph defined in the baseEncoding
             // seems to yield a better `toUnicode` mapping (fixes issue 5070).

test/pdfs/.gitignore

@@ -236,6 +236,7 @@
 !issue4061.pdf
 !issue4668.pdf
 !PDFJS-7562-reduced.pdf
+!issue11768_reduced.pdf
 !issue5039.pdf
 !issue5070.pdf
 !issue5238.pdf

test/test_manifest.json

@@ -3109,6 +3109,12 @@
        "type": "text",
        "about": "Invisible (and broken) TrueType font used for text-selection."
     },
+    {  "id": "issue11768",
+       "file": "pdfs/issue11768_reduced.pdf",
+       "md5": "0cafde97d78bb6883531a325a996a5ef",
+       "rounds": 1,
+       "type": "eq"
+    },
     {  "id": "issue1912",
       "file": "pdfs/issue1912.pdf",
       "md5": "15305b7c2cba971e7423de3f6ad38fef",