fixing issue gwtproject#10181: don't call setInstantiable(...) for class still having a chance of instantiability

Author: axeluhl

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

@@ -1272,7 +1272,9 @@ private boolean checkSubtypes(TreeLogger logger, JClassType originalType,
       boolean instantiable =
           checkSubtype(subtypeLogger, candidate, originalType, subtypePath, problems);
       anySubtypes |= instantiable;
-      tic.setInstantiable(instantiable);
+      if (instantiable) {
+        tic.setInstantiable(true);
+      }
 
       if (instantiable) {
         subtypeLogger.branch(TreeLogger.DEBUG, "Is instantiable");
@@ -1285,6 +1287,9 @@ private boolean checkSubtypes(TreeLogger logger, JClassType originalType,
         instSubtypes.add(candidate);
       }
     }
+    if (!anySubtypes) {
+      tic.setInstantiable(false);
+    }
 
     return anySubtypes;
   }