Had old IR serialization logic for chilled string

Author: enebo

core/src/main/java/org/jruby/ir/operands/ChilledString.java

@@ -16,6 +16,10 @@ public ChilledString(ByteList bytelist, int coderange, String file, int line) {
         super(bytelist, coderange, file, line);
     }
 
+    public ChilledString(FrozenString frozenString) {
+        super(frozenString);
+    }
+
     @Override
     public OperandType getOperandType() {
         return OperandType.CHILLED_STRING;
@@ -42,6 +46,6 @@ public void visit(IRVisitor visitor) {
     }
 
     public static ChilledString decode(IRReaderDecoder d) {
-        return new ChilledString(d.decodeByteList(), d.decodeInt(), d.decodeString(), d.decodeInt());
+        return new ChilledString((FrozenString)d.decodeOperand());
     }
 }

core/src/main/java/org/jruby/ir/operands/MutableString.java

@@ -37,7 +37,7 @@ public MutableString(RubySymbol symbol) {
         frozenString = new FrozenString(symbol);
     }
 
-    private MutableString(FrozenString frozenString) {
+    protected MutableString(FrozenString frozenString) {
         this.frozenString = frozenString;
     }