Merge upstream.

diff --cc src/canvas.js
Simple merge

diff --cc test/test_manifest.json
index aab83880758a6caa395afb4bfbd2c4b4ec3203e6,fba8df6657249de9f1ac9722e761269946cacb52..7469db678501d8d49cb9faeaa30f64d0c3a18a1a
--- 1/test/test_manifest.json
--- 2/test/test_manifest.json
+++ b/test/test_manifest.json
@@@ -349,11 -349,10 +349,17 @@@
         "pageLimit": 3,
         "type": "eq"
      },
+     {  "id": "issue918",
+        "file": "pdfs/issue918.pdf",
+        "md5": "d582cc0f2592ae82936589ced2a47e55",
+        "rounds": 1,
+        "type": "eq"
++    },
 +    {  "id": "aboutstacks",
 +      "file": "pdfs/aboutstacks.pdf",
 +      "md5": "6e7c8416a293ba2d83bc8dd20c6ccf51",
 +      "rounds": 1,
 +      "link": true,
 +      "type": "eq"
      }
  ]