Simplify AST ID generation.

src/parser.h

Index: src/parser.h
diff --git a/src/parser.h b/src/parser.h
index 7d77767743b89de5f683055dd211f762dab8335c..19ed18539a36e1ddd80efc55d7b8f7568de5756b 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -376,21 +376,6 @@ class ParserTraits {
 
   explicit ParserTraits(Parser* parser) : parser_(parser) {}
 
-  // Custom operations executed when FunctionStates are created and destructed.
-  template <typename FunctionState>
-  static void SetUpFunctionState(FunctionState* function_state) {
-    function_state->saved_id_gen_ = *function_state->ast_node_id_gen_;
-    *function_state->ast_node_id_gen_ =
-        AstNode::IdGen(BailoutId::FirstUsable().ToInt());
-  }
-
-  template <typename FunctionState>
-  static void TearDownFunctionState(FunctionState* function_state) {
-    if (function_state->outer_function_state_ != NULL) {
-      *function_state->ast_node_id_gen_ = function_state->saved_id_gen_;
-    }
-  }
-
   // Helper functions for recursive descent.
   bool IsEvalOrArguments(const AstRawString* identifier) const;
   V8_INLINE bool IsFutureStrictReserved(const AstRawString* identifier) const;