Tidy up and rename method for creating dummy encodings.

Author: aardvark179

src/main/java/org/truffleruby/core/encoding/EncodingManager.java

@@ -261,13 +261,13 @@ public DynamicObject defineAlias(Encoding encoding, String name) {
     }
 
     @TruffleBoundary
-    public synchronized DynamicObject dummyEncoding(String name) {
+    public synchronized DynamicObject createDummyEncoding(String name) {
         if (getRubyEncoding(name) != null) {
             return null;
         }
 
-        EncodingDB.dummy(name);
         byte[] nameBytes = name.getBytes();
+        EncodingDB.dummy(nameBytes);
         final Entry entry = EncodingDB.getEncodings().get(nameBytes);
         return defineEncoding(entry, nameBytes, 0, nameBytes.length);
     }

src/main/java/org/truffleruby/core/encoding/EncodingNodes.java

@@ -680,7 +680,7 @@ private DynamicObject replicate(String name, Encoding encoding) {
     public static abstract class DummyEncodingeNode extends PrimitiveArrayArgumentsNode {
 
         @Specialization(guards = "isRubyString(nameObject)")
-        public DynamicObject dummyEncoding(DynamicObject nameObject) {
+        public DynamicObject createDummyEncoding(DynamicObject nameObject) {
             final String name = StringOperations.getString(nameObject);
 
             final DynamicObject newEncoding = dummy(name);
@@ -694,7 +694,7 @@ public DynamicObject dummyEncoding(DynamicObject nameObject) {
 
         @TruffleBoundary
         private DynamicObject dummy(String name) {
-            return getContext().getEncodingManager().dummyEncoding(name);
+            return getContext().getEncodingManager().createDummyEncoding(name);
         }
 
     }