Redo illustration in Object Pool.

Author: munificent

book/object-pool.markdown

@@ -47,7 +47,7 @@ That's fragmentation.
 
 <span name="heap"></span>
 
-<img src="images/object-pool-heap-fragment.gif" />
+<img src="images/object-pool-heap-fragment.png" />
 
 <aside name="heap">
 

html/images/object-pool-heap-fragment.gif

@@ -97,7 +97,7 @@ <h3><a href="#the-curse-of-fragmentation" name="the-curse-of-fragmentation">The
 </aside>
 
 <p><span name="heap"></span></p>
-<p><img src="images/object-pool-heap-fragment.gif" /></p>
+<p><img src="images/object-pool-heap-fragment.png" /></p>
 <aside name="heap">
 
 <p>Here&#x2019;s how a heap becomes fragmented, and how it can cause an