remove incorrect assertion

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

@@ -148,7 +148,6 @@ public final class RStringVector extends RVector implements RAbstractStringVecto
     }
 
     private String[] createResizedData(int size, String fill) {
-        assert !this.isShared();
         return copyResizedData(size, fill);
     }