Experimental parser: elide cursor reads in some cases

tools/lexer_generator/code_generator.jinja

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 187 matching lines @@
 {% endmacro -%}
 
 
 {%- macro do_dfa_state(node_number_chain) -%}
 
   {%- set node_number = node_number_chain|first -%}
   {%- set state = dfa_states[node_number] -%}
 
   {{ write_label('state_entry', node_number_chain) }}
 
-  READ_CURSOR();
+  {% if not state['can_elide_read'] -%}
+    READ_CURSOR();
+  {%- endif -%}
 
   {% if debug_print %}
     fprintf(stderr,
             "state {{state.node_number}}, start %d, cursor %d\n",
             start_ - buffer_,
             cursor_ - buffer_);
   {% endif -%}
 
   {%- set entry_action = state.entry_action -%}
   {%- if entry_action %}
@@ skipping 125 matching lines @@
     // force use of stored_token
     stored_token = Token::ILLEGAL;
     // force use of marker
     marker = NULL;
     // force use of state_entry_0
     goto state_entry_0;
   }
 }
 } }