Add support to trace preparsing decisions

src/parsing/preparser.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <cmath>
 
 #include "src/allocation.h"
 #include "src/base/logging.h"
 #include "src/conversions-inl.h"
 #include "src/conversions.h"
@@ skipping 159 matching lines @@
   language_mode = function_scope->language_mode();
 
   // Validate name and parameter names. We can do this only after parsing the
   // function, since the function can declare itself strict.
   CheckFunctionName(language_mode, function_name, function_name_validity,
                     function_name_location, CHECK_OK);
   const bool allow_duplicate_parameters =
       is_sloppy(language_mode) && formals.is_simple && !IsConciseMethod(kind);
   ValidateFormalParameters(language_mode, allow_duplicate_parameters, CHECK_OK);
 
+  int end_position = scanner()->location().end_pos;
   if (is_strict(language_mode)) {
-    int end_position = scanner()->location().end_pos;
     CheckStrictOctalLiteral(start_position, end_position, CHECK_OK);
     CheckDecimalLiteralWithLeadingZero(start_position, end_position);
   }
+  function_scope->set_end_position(end_position);
+
+  if (FLAG_trace_preparse) {
+    PrintF("  [%s]: %i-%i\n",
+           track_unresolved_variables_ ? "Preparse resolution"
+                                       : "Preparse no-resolution",
+           function_scope->start_position(), function_scope->end_position());
+  }
 
   return Expression::Default();
 }
 
 PreParser::LazyParsingResult PreParser::ParseStatementListAndLogFunction(
     bool may_abort, bool* ok) {
   int body_start = position();
   PreParserStatementList body;
   LazyParsingResult result = ParseStatementList(
       body, Token::RBRACE, may_abort, CHECK_OK_VALUE(kLazyParsingComplete));
@@ skipping 51 matching lines @@
     }
   }
 }
 
 #undef CHECK_OK
 #undef CHECK_OK_CUSTOM
 
 
 }  // namespace internal
 }  // namespace v8