Remove outdated gwt-maven repository

This repository hasn't had an update since before GWT 1.5 came out.

Change-Id: I464e7291406825185fb2741627f9a58a06e05cb4
Signed-off-by: Shawn O. Pearce <sop@google.com>
diff --git a/pom.xml b/pom.xml
index de1e587..f77478a 100644
--- a/pom.xml
+++ b/pom.xml
@@ -409,10 +409,6 @@
       <id>objectweb-repository</id>
       <url>http://maven.objectweb.org/maven2</url>
     </repository>
-    <repository>
-      <id>gwt-maven</id>
-      <url>http://gwt-maven.googlecode.com/svn/trunk/mavenrepo/</url>
-    </repository>
   </repositories>
 
   <distributionManagement>