Correctly access `colorSpace.numComps` in `MeshStreamReader` (issue 6287)

This regressed in f750e35224.

src/core/pattern.js

@@ -225,7 +225,7 @@ Shadings.Mesh = (function MeshClosure() {
 
     var numComps = context.numComps;
     this.tmpCompsBuf = new Float32Array(numComps);
-    var csNumComps = context.colorSpace;
+    var csNumComps = context.colorSpace.numComps;
     this.tmpCsCompsBuf = context.colorFn ? new Float32Array(csNumComps) :
                                            this.tmpCompsBuf;
   }

test/pdfs/.gitignore

@@ -23,6 +23,7 @@
 !sizes.pdf
 !close-path-bug.pdf
 !issue2948.pdf
+!issue6231_1.pdf
 !issue4630.pdf
 !issue4909.pdf
 !issue5202.pdf

test/test_manifest.json

@@ -641,6 +641,13 @@
        "rounds": 1,
        "type": "eq"
     },
+    {  "id": "issue6231_1",
+       "file": "pdfs/issue6231_1.pdf",
+       "md5": "eb13a9366a5142833a858472c68b4749",
+       "link": false,
+       "rounds": 1,
+       "type": "eq"
+    },
     {  "id": "usmanm-bad-auto-fetch",
        "file": "pdfs/usmanm-bad.pdf",
        "md5": "38afb822433aaf07fc8f54807cd4f61a",