Adds more SMask tests.

test/pdfs/.gitignore

@@ -215,6 +215,7 @@
 !issue6069.pdf
 !issue6106.pdf
 !issue6296.pdf
+!bug852992_reduced.pdf
 !issue6298.pdf
 !issue6889.pdf
 !bug1001080.pdf

test/pdfs/bug1199237.pdf.link

@@ -0,0 +1 @@
+https://bugzilla.mozilla.org/attachment.cgi?id=8653724

test/pdfs/issue6165.pdf.link

@@ -0,0 +1 @@
+http://web.archive.org/web/20160405054842/http://www.sec.gov/investor/pubs/sec-guide-to-proxy-brochures.pdf

test/test_manifest.json

@@ -1503,6 +1503,33 @@
       "link": true,
       "type": "eq"
     },
+    {
+      "id": "bug852992",
+      "file": "pdfs/bug852992_reduced.pdf",
+      "md5": "c11439fe3b7f8bc39d89dcff58c50a0c",
+      "rounds": 1,
+      "type": "eq"
+    },
+    {
+      "id": "bug1199237",
+      "file": "pdfs/bug1199237.pdf",
+      "md5": "e9a63d3207ccc65a4955d5723546e962",
+      "rounds": 1,
+      "firstPage": 1,
+      "lastPage": 1,
+      "link": true,
+      "type": "eq"
+    },
+    {
+      "id": "issue6165",
+      "file": "pdfs/issue6165.pdf",
+      "md5": "84ebde43b9121aa2ef8026388a4f4244",
+      "rounds": 1,
+      "firstPage": 1,
+      "lastPage": 1,
+      "link": true,
+      "type": "eq"
+    },
     {
       "id": "issue6019-text",
       "file": "pdfs/issue6019.pdf",