Minor refactoring that reduces code duplication.

com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/data/RSequence.java

@@ -157,16 +157,7 @@ public abstract class RSequence implements RAbstractVector {
 
     @Override
     public final RVector materializeNonShared() {
-        RVector resultVector = this.materialize();
-        assert !resultVector.isShared();
-        // marking non-temp must be consistent with what RVector does, otherwise the following code
-        // will not work:
-        // x<-1:3 ; attr(x, "myatt")<-2:4 ; y <- x; attr(x, "myatt1")<-"hello" ; attributes(y)
-        if (FastROptions.NewStateTransition.getBooleanValue()) {
-            resultVector.incRefCount();
-        } else {
-            resultVector.markNonTemporary();
-        }
+        RVector resultVector = this.materialize().materializeNonShared();
         return resultVector;
     }