Add a reduced test case for issue 4379

This should have been part of PR 5136.

Based on comments https://github.com/mozilla/pdf.js/issues/4379#issuecomment-51221787 and https://github.com/mozilla/pdf.js/issues/4379#issuecomment-51475463, it should be OK to include the PDF file in the repo.

test/pdfs/.gitignore

@@ -39,6 +39,7 @@
 !issue2931.pdf
 !issue3323.pdf
 !issue4304.pdf
+!issue4379.pdf
 !issue4550.pdf
 !bug1011159.pdf
 !issue4875.pdf

test/test_manifest.json

@@ -944,6 +944,13 @@
        "rounds": 1,
        "type": "eq"
     },
+    {  "id": "issue4379",
+       "file": "pdfs/issue4379.pdf",
+       "md5": "09715ec1a7b0f3a7ae02b3046f627b9f",
+       "link": false,
+       "rounds": 1,
+       "type": "eq"
+    },
     {  "id": "issue4722",
        "file": "pdfs/issue4722.pdf",
        "md5": "a42ca858af7d179358f92f47e57c0fed",