Delete UiBinder's temporary files on exit

Review by bobv
Test by inspection of /tmp

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@6495 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/user/src/com/google/gwt/uibinder/rebind/model/ImplicitCssResource.java b/user/src/com/google/gwt/uibinder/rebind/model/ImplicitCssResource.java
index 588921e..747e6b6 100644
--- a/user/src/com/google/gwt/uibinder/rebind/model/ImplicitCssResource.java
+++ b/user/src/com/google/gwt/uibinder/rebind/model/ImplicitCssResource.java
@@ -180,6 +180,7 @@
       try {
         File f = File.createTempFile(String.format("uiBinder_%s_%s",
             packageName, className), ".css");
+        f.deleteOnExit();
 
         BufferedWriter out = new BufferedWriter(new FileWriter(f));
         out.write(body);