Improve performance by not de-duping before closing

You close *after* you've determined that a successor is new, not
before.

grammar.py

@@ -256,11 +256,8 @@ class FineGrammar(Grammar):
     def primary_expression(self) -> Rule:
         return (
             self.identifier_expression
+            | self.literal_expression
             | SELF
-            | NUMBER
-            | STRING
-            | TRUE
-            | FALSE
             | seq(BANG, self.primary_expression)
             | seq(MINUS, self.primary_expression)
             | self.block
@@ -278,6 +275,10 @@ class FineGrammar(Grammar):
     def identifier_expression(self):
         return IDENTIFIER
 
+    @rule("Literal")
+    def literal_expression(self):
+        return NUMBER | STRING | TRUE | FALSE
+
     @rule("ConditionalExpression")
     def conditional_expression(self) -> Rule:
         return (