Fixes Shading.Dummy return type

src/pattern.js

@@ -38,6 +38,7 @@ var Pattern = (function PatternClosure() {
         // Both radial and axial shadings are handled by RadialAxial shading.
         return new Shadings.RadialAxial(dict, matrix, xref, res);
       default:
+        TODO('Unsupported shading type: ' + type);
         return new Shadings.Dummy();
     }
   };
@@ -174,7 +175,12 @@ Shadings.Dummy = (function DummyClosure() {
   }
 
   Dummy.fromIR = function Dummy_fromIR() {
+    return {
+      type: 'Pattern',
+      getPattern: function Dummy_fromIR_getPattern() {
         return 'hotpink';
+      }
+    };
   };
 
   Dummy.prototype = {