Bug 691976 - NULL check the JSContext before using JS_updateMallocCounter. r=Bas

content/canvas/src/nsCanvasRenderingContext2DAzure.cpp

@@ -1264,7 +1264,10 @@ nsCanvasRenderingContext2DAzure::SetDimensions(PRInt32 width, PRInt32 height)
     }
 
     gCanvasAzureMemoryUsed += width * height * 4;
-    JS_updateMallocCounter(nsContentUtils::GetCurrentJSContext(), width * height * 4);
+    JSContext* context = nsContentUtils::GetCurrentJSContext();
+    if (context) {
+      JS_updateMallocCounter(context, width * height * 4);
+    }
   }
 
   return InitializeWithTarget(target, width, height);