Enables on the persistent unit cache by default.

Review at http://gwt-code-reviews.appspot.com/1448801


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@10202 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/dev/core/src/com/google/gwt/dev/javac/UnitCacheFactory.java b/dev/core/src/com/google/gwt/dev/javac/UnitCacheFactory.java
index 6b1ef43..75d8bb5 100644
--- a/dev/core/src/com/google/gwt/dev/javac/UnitCacheFactory.java
+++ b/dev/core/src/com/google/gwt/dev/javac/UnitCacheFactory.java
@@ -29,7 +29,7 @@
    * The API must be enabled explicitly for persistent caching to be live.
    */
   private static final String configPropertyValue = System.getProperty("gwt.persistentunitcache",
-      "false");
+      "true");
   private static final boolean usePersistent = configPropertyValue.length() == 0
       || Boolean.parseBoolean(configPropertyValue);
   private static UnitCache instance = null;