Optimize returned parameter only when all possible callees are visible.

Author: cstancu

substratevm/src/com.oracle.graal.pointsto/src/com/oracle/graal/pointsto/results/StrengthenGraphs.java

@@ -739,7 +739,8 @@ private void handleInvoke(Invoke invoke, SimplifierTool tool) {
                 }
             }
 
-            if (allowOptimizeReturnParameter) {
+            if (allowOptimizeReturnParameter && (isClosedTypeWorld || callTarget.invokeKind().isDirect() || targetMethod.canBeStaticallyBound())) {
+                /* Can only optimize returned parameter when all possible callees are visible. */
                 optimizeReturnedParameter(callees, arguments, node, tool);
             }