Add a dummy byte at end of the CFF table to satisfy sanitizer

Fixes #2674.

src/fonts.js

@@ -6581,6 +6581,10 @@ var CFFCompiler = (function CFFCompilerClosure() {
 
       this.compilePrivateDicts([cff.topDict], [topDictTracker], output);
 
+      // If the font data ends with INDEX whose object data is zero-length,
+      // the sanitizer will bail out. Add a dummy byte to avoid that.
+      output.add([0]);
+
       return output.data;
     },
     encodeNumber: function CFFCompiler_encodeNumber(value) {

test/pdfs/JST2007-5.pdf.link

@@ -0,0 +1 @@
+http://kanji.zinbun.kyoto-u.ac.jp/%7Eyasuoka/publications/JST2007-5.pdf

test/test_manifest.json

@@ -876,6 +876,15 @@
       "rounds": 1,
       "type": "eq"
     },
+    {  "id": "jst2007-5",
+      "file": "pdfs/JST2007-5.pdf",
+      "md5": "9efa6c37fc771b36a60535036d1910bb",
+      "rounds": 1,
+      "link": true,
+      "firstPage": 2,
+      "lastPage": 2,
+      "type": "eq"
+    },
     {  "id": "noembed-identity",
       "file": "pdfs/noembed-identity.pdf",
       "md5": "05d3803b6c22451e18cb60d8d8c75c0c",