[es6] implement default/optional parameters (WIP / comments)

src/preparser.h

 // Copyright 2012 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.
 
 #ifndef V8_PREPARSER_H
 #define V8_PREPARSER_H
 
 #include "src/v8.h"
 
 #include "src/bailout-reason.h"
@@ skipping 1178 matching lines @@
     return PreParserExpression::Default();
   }
   PreParserStatement NewReturnStatement(PreParserExpression expression,
                                         int pos) {
     return PreParserStatement::Default();
   }
   PreParserExpression NewFunctionLiteral(
       PreParserIdentifier name, AstValueFactory* ast_value_factory,
       Scope* scope, PreParserStatementList body, int materialized_literal_count,
       int expected_property_count, int handler_count, int parameter_count,
+      PreParserExpressionList default_values,
       FunctionLiteral::ParameterFlag has_duplicate_parameters,
       FunctionLiteral::FunctionType function_type,
       FunctionLiteral::IsFunctionFlag is_function,
       FunctionLiteral::IsParenthesizedFlag is_parenthesized, FunctionKind kind,
       int position) {
     return PreParserExpression::Default();
   }
 
   PreParserExpression NewSpread(PreParserExpression expression, int pos) {
     return PreParserExpression::Spread(expression);
@@ skipping 1859 matching lines @@
         eval_args_error_loc, dupe_error_loc, reserved_loc, CHECK_OK);
 
     // Validate strict mode.
     if (is_strict(language_mode())) {
       CheckStrictOctalLiteral(start_pos, scanner()->location().end_pos,
                               CHECK_OK);
       this->CheckConflictingVarDeclarations(scope, CHECK_OK);
     }
   }
 
+  typename Traits::Type::ExpressionList default_values =
+      this->NewExpressionList(0, zone_);
   FunctionLiteralT function_literal = factory()->NewFunctionLiteral(
       this->EmptyIdentifierString(), ast_value_factory(), scope, body,
       materialized_literal_count, expected_property_count, handler_count,
-      num_parameters, FunctionLiteral::kNoDuplicateParameters,
+      num_parameters, default_values, FunctionLiteral::kNoDuplicateParameters,
       FunctionLiteral::ANONYMOUS_EXPRESSION, FunctionLiteral::kIsFunction,
       FunctionLiteral::kNotParenthesized, FunctionKind::kArrowFunction,
       start_pos);
 
   function_literal->set_function_token_position(start_pos);
   if (super_loc.IsValid()) function_state_->set_super_call_location(super_loc);
 
   if (fni_ != NULL) this->InferFunctionName(fni_, function_literal);
 
   return function_literal;
@@ skipping 170 matching lines @@
       *ok = false;
       return;
     }
     has_seen_constructor_ = true;
     return;
   }
 }
 } }  // v8::internal
 
 #endif  // V8_PREPARSER_H