Don't generate image files if there aren't any.

Reviewed by me.

Objective-J/CommonJS/lib/objective-j/jake/bundletask.js

@@ -350,6 +350,11 @@ BundleTask.prototype.packageType = function()
     return 1;
 }
 
+function isDataResource(aFilename)
+{
+    return FILE.isFile(aFilename) && isImage(aFilename);
+}
+
 BundleTask.prototype.infoPlist = function()
 {
     var infoPlistPath = this.infoPlistPath();
@@ -370,14 +375,17 @@ BundleTask.prototype.infoPlist = function()
         return anEnvironment.name();
     }));
     infoPlist.setValueForKey("CPBundleExecutable", this.productName() + ".sj");
-    infoPlist.setValueForKey("CPBundleEnvironmentsWithImageSprites", this.environments().filter(
+
+    var environmentsWithImageSprites = this.environments().filter(
     function(anEnvironment)
     {
-        return anEnvironment.spritesImages();
-    }).map(function(anEnvironment)
+        return anEnvironment.spritesImages() && task(this.buildProductDataURLPathForEnvironment(anEnvironment)).prerequisites().filter(isDataResource).length > 0;
+    }, this).map(function(anEnvironment)
     {
         return anEnvironment.name();
-    }));
+    });
+
+    infoPlist.setValueForKey("CPBundleEnvironmentsWithImageSprites", environmentsWithImageSprites);
 
     var principalClass = this.principalClass();
 
@@ -581,7 +589,6 @@ BundleTask.prototype.defineResourceTasks = function()
     }, this);
 }
 
-
 var RESOURCES_PATH  = FILE.join(FILE.absolute(FILE.dirname(module.path)), "RESOURCES"),
     MHTMLTestPath   = FILE.join(RESOURCES_PATH, "MHTMLTest.txt");
 
@@ -595,11 +602,6 @@ BundleTask.prototype.defineSpritedImagesTask = function()
         var folder = anEnvironment.name() + ".environment",
             resourcesPath = FILE.join(this.buildIntermediatesProductPath(), folder, "Resources", "");
 
-        function isDataResource(aFilename)
-        {
-            return FILE.isFile(aFilename) && aFilename.indexOf(resourcesPath) === 0 && isImage(aFilename);
-        }
-
         var productName = this.productName(),
             dataURLPath = this.buildProductDataURLPathForEnvironment(anEnvironment);