Implement "skipPages" feature for reftests

test/driver.js

@@ -107,6 +107,13 @@ function nextPage(task, loadError) {
     }
   }
 
+  if (task.skipPages && task.skipPages.indexOf(task.pageNum) >= 0) {
+    log(' skipping page ' + task.pageNum + '/' + task.pdfDoc.numPages +
+        '... ');
+    snapshotCurrentPage(task, '');
+    return;
+  }
+
   var page = null;
 
   if (!failure) {

test/pdfs/ibwa-bad.pdf.link

@@ -0,0 +1 @@
+http://www.bottledwater.org/public/pdf/IBWA05ModelCode_Mar2.pdf

test/test_manifest.json

@@ -151,5 +151,12 @@
        "link": true,
        "rounds": 1,
        "type": "load"
+    },
+    {  "id": "ibwa-bad",
+       "file": "pdfs/ibwa-bad.pdf",
+       "link": true,
+       "rounds": 1,
+       "skipPages": [ 16 ],
+       "type": "load"
     }
 ]