Cherry-pick r10451 into GWT 2.4 branch.
Add StringKey to gwt-servlet.jar.


git-svn-id: https://google-web-toolkit.googlecode.com/svn/releases/2.4@10453 8db76d5a-ed1c-0410-87a9-c151d255dfc7

servlet/build.xml

diff --git a/servlet/build.xml b/servlet/build.xml
index c33229f..dcb9a83 100755
--- a/servlet/build.xml
+++ b/servlet/build.xml
@@ -26,6 +26,7 @@
       <fileset dir="${gwt.dev.bin}">
         <include name="com/google/gwt/dev/asm/**" />
         <include name="com/google/gwt/dev/util/Name*.class" />
+        <include name="com/google/gwt/dev/util/StringKey.class" />
       </fileset>
       <fileset dir="${gwt.user.bin}">
         <exclude name="**/rebind/**" />