Use RopeOperations.withEncoding() instead of the internal Rope#withEncoding()

Author: eregon

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

@@ -722,7 +722,7 @@ public static Rope quote19(Rope bs) {
                 p += cl;
             }
             if (asciiOnly) {
-                return bs.withEncoding(USASCIIEncoding.INSTANCE, CR_7BIT);
+                return RopeOperations.withEncoding(bs, USASCIIEncoding.INSTANCE);
             }
             return bs;
         } while (false);

src/main/java/org/truffleruby/core/rope/RepeatingRope.java

@@ -34,7 +34,7 @@ public RepeatingRope(ManagedRope child, int times) {
 
     @Override
     public Rope withEncoding(Encoding newEncoding, CodeRange newCodeRange) {
-        return new RepeatingRope((ManagedRope) child.withEncoding(newEncoding, newCodeRange), times);
+        return new RepeatingRope((ManagedRope) RopeOperations.withEncoding(child, newEncoding), times);
     }
 
     @Override

src/main/java/org/truffleruby/core/symbol/SymbolTable.java

@@ -131,7 +131,7 @@ private RopeKey createRopeKey(Rope rope) {
         }
 
         if (rope.isAsciiOnly() && rope.getEncoding() != USASCIIEncoding.INSTANCE) {
-            rope = rope.withEncoding(USASCIIEncoding.INSTANCE, CodeRange.CR_7BIT);
+            rope = RopeOperations.withEncoding(rope, USASCIIEncoding.INSTANCE);
         }
 
         return new RopeKey(rope, hashing);