Fixed the insertion mistake.

Oops.

Author: Abhishek Hingnikar

lib/ImageCache.js

@@ -154,7 +154,7 @@ var ImageCache = {
  if (_instancePool.length >= kInstancePoolLength) {
  _instancePool.popLeastUsed().destructor();
  }
- _instancePool.push(image);
+ _instancePool.push(image.getOriginalSrc(), image);
  }
  return image;
  }