Remove dead code as the result of recent cleanups

Author: eregon

src/main/java/org/truffleruby/language/loader/CodeLoader.java

@@ -53,9 +53,8 @@ public CodeLoader(RubyLanguage language, RubyContext context) {
     @TruffleBoundary
     public RootCallTarget parseTopLevelWithCache(RubySource rubySource, Node currentNode) {
         final Source source = rubySource.getSource();
-        var tstringWithEncoding = rubySource.getTStringWithEncoding();
-
         final String path = RubyLanguage.getPath(source);
+
         if (language.singleContext && !alreadyLoadedInContext.add(language.getPathRelativeToHome(path))) {
             /* Duplicate load of the same file in the same context, we cannot use the cache because it would re-assign
              * the live modules of static LexicalScopes and we cannot/do not want to invalidate static LexicalScopes, so

src/main/java/org/truffleruby/parser/lexer/RubyLexer.java

@@ -60,7 +60,6 @@
 import com.oracle.truffle.api.strings.TruffleString;
 import com.oracle.truffle.api.strings.TruffleString.ErrorHandling;
 import org.jcodings.Encoding;
-import org.jcodings.specific.USASCIIEncoding;
 import org.jcodings.specific.UTF8Encoding;
 import org.truffleruby.RubyContext;
 import org.truffleruby.annotations.SuppressFBWarnings;
@@ -464,10 +463,6 @@ protected void setEncoding(TruffleString name) {
         setEncoding(newEncoding);
     }
 
-    private boolean isUTF8Subset(Encoding encoding) {
-        return encoding == UTF8Encoding.INSTANCE || encoding == USASCIIEncoding.INSTANCE;
-    }
-
     private RuntimeException argumentError(RubyContext context, String message) {
         if (context != null) {
             return new RaiseException(context, context.getCoreExceptions().argumentError(message, null));
@@ -1400,20 +1395,6 @@ public boolean onMagicComment(String name, TruffleString value) {
         return false;
     }
 
-    private static boolean isKnownMagicComment(String name) {
-        if (isMagicEncodingComment(name)) {
-            return true;
-        } else if ("frozen_string_literal".equalsIgnoreCase(name)) {
-            return true;
-        } else if ("warn_indent".equalsIgnoreCase(name)) {
-            return true;
-        } else if ("truffleruby_primitives".equalsIgnoreCase(name)) {
-            return true;
-        } else {
-            return false;
-        }
-    }
-
     public static boolean isMagicEncodingComment(String name) {
         return "coding".equalsIgnoreCase(name) || "encoding".equalsIgnoreCase(name);
     }