Add logic needed for calculating the offset of a stack slot in an entry point.

Author: MichaelHaas99

src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/code/StackSlot.java

@@ -132,4 +132,25 @@ public boolean equals(Object obj) {
         }
         return false;
     }
+
+    // TODO: can we somehow avoid this?
+    private boolean isOldArgument;
+    private boolean isNewArgument;
+
+    public boolean isOldArgument() {
+        return isOldArgument;
+    }
+
+    public boolean isNewArgument() {
+        return isNewArgument;
+    }
+
+    public void setOldArgument(boolean oldArgument) {
+        this.isOldArgument = oldArgument;
+    }
+
+    public void setNewArgument(boolean newArgument) {
+        this.isNewArgument = newArgument;
+    }
+
 }