Remove duplicate RopeCache lookup

Author: eregon

src/main/java/org/truffleruby/core/regexp/RegexpNodes.java

@@ -38,6 +38,7 @@
 import org.truffleruby.core.regexp.RegexpNodesFactory.ToSNodeFactory;
 import org.truffleruby.core.rope.CodeRange;
 import org.truffleruby.core.rope.Rope;
+import org.truffleruby.core.rope.RopeOperations;
 import org.truffleruby.core.string.RubyString;
 import org.truffleruby.core.string.StringNodes;
 import org.truffleruby.core.symbol.RubySymbol;
@@ -221,7 +222,7 @@ protected RubyArray regexpNames(RubyRegexp regexp) {
                 final NameEntry e = iter.next();
                 final byte[] bytes = Arrays.copyOfRange(e.name, e.nameP, e.nameEnd);
 
-                final Rope rope = getLanguage().ropeCache.getRope(bytes, UTF8Encoding.INSTANCE, CodeRange.CR_UNKNOWN);
+                final Rope rope = RopeOperations.create(bytes, UTF8Encoding.INSTANCE, CodeRange.CR_UNKNOWN);
                 final RubySymbol name = getSymbol(rope);
 
                 final int[] backrefs = e.getBackRefs();