Fix bad assertion.

Patch by: bobv
Review by: amitmanjhi (TBR)

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@5765 8db76d5a-ed1c-0410-87a9-c151d255dfc7

user/src/com/google/gwt/rpc/rebind/RpcProxyCreator.java

diff --git a/user/src/com/google/gwt/rpc/rebind/RpcProxyCreator.java b/user/src/com/google/gwt/rpc/rebind/RpcProxyCreator.java
index 2467976..5d277be 100644
--- a/user/src/com/google/gwt/rpc/rebind/RpcProxyCreator.java
+++ b/user/src/com/google/gwt/rpc/rebind/RpcProxyCreator.java
@@ -304,10 +304,10 @@
         deserializationSto.getSerializableTypes());
     for (JMethod m : serviceIntf.getOverridableMethods()) {
       // Pick up any primitive return types, which get sent boxed
-      assert serializableTypes.contains(m.getReturnType())
-          || m.getReturnType().isPrimitive() != null : "Missing non-primitive return type "
-          + m.getReturnType().getQualifiedSourceName();
-      serializableTypes.add(m.getReturnType());
+      JPrimitiveType mustBox = m.getReturnType().isPrimitive();
+      if (mustBox != null) {
+        serializableTypes.add(m.getReturnType());
+      }
     }
 
     StringBuilder sb = new StringBuilder("@ArtificialRescue({");