Type bounds compatibility fix.

Suggested by: amitmanjhi


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@2529 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/user/super/com/google/gwt/emul/java/util/TreeMap.java b/user/super/com/google/gwt/emul/java/util/TreeMap.java
index a226ff1..645fd15 100644
--- a/user/super/com/google/gwt/emul/java/util/TreeMap.java
+++ b/user/super/com/google/gwt/emul/java/util/TreeMap.java
@@ -24,8 +24,7 @@
  * @param <K> key type
  * @param <V> value type
  */
-public class TreeMap<K extends Comparable<K>, V> extends AbstractMap<K, V>
-    implements SortedMap<K, V> {
+public class TreeMap<K, V> extends AbstractMap<K, V> implements SortedMap<K, V> {
   /*
    * Implementation derived from public domain C implementation as of 5
    * September 2007 at: