Fixes stream loading for XRefStm

src/obj.js

@@ -710,6 +710,7 @@ var XRef = (function XRefClosure() {
         error('invalid first and n parameters for ObjStm stream');
       }
       parser = new Parser(new Lexer(stream), false, this);
+      parser.allowStreams = true;
       var i, entries = [], nums = [];
       // read the object numbers to populate cache
       for (i = 0; i < n; ++i) {

test/pdfs/issue2337.pdf.link

@@ -0,0 +1 @@
+http://mirrors.ctan.org/info/lshort/english/lshort.pdf

test/test_manifest.json

@@ -727,6 +727,14 @@
       "rounds": 1,
       "type": "load"
     },
+    {  "id": "issue2337",
+      "file": "pdfs/issue2337.pdf",
+      "md5": "ea10f4131202b9b8f2a6cb7770d3f185",
+      "rounds": 1,
+      "pageLimit": 1,
+      "link": true,
+      "type": "load"
+    },
     {  "id": "issue2074",
       "file": "pdfs/issue2074.pdf",
       "md5": "5e4ba2241fc35d20e44eb52289a569ab",