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

src/ast.h

Index: src/ast.h
diff --git a/src/ast.h b/src/ast.h
index 7bfa02178faabb6e09af3c3f8d8f303393da88d1..90f5cb8eb240f8a4da0a136f21791335a47bc234 100644
--- a/src/ast.h
+++ b/src/ast.h
@@ -1348,6 +1348,7 @@ class Literal FINAL : public Expression {
 
   Handle<Object> value() const { return value_->value(); }
   const AstValue* raw_value() const { return value_; }
+  bool IsUndefined() const { return value_->IsUndefined(); }
 
   // Support for using Literal as a HashMap key. NOTE: Currently, this works
   // only for string and number literals!
@@ -2505,6 +2506,7 @@ class FunctionLiteral FINAL : public Expression {
   const AstRawString* raw_name() const { return raw_name_; }
   Scope* scope() const { return scope_; }
   ZoneList<Statement*>* body() const { return body_; }
+  ZoneList<Expression*>* default_values() const { return default_values_; }
   void set_function_token_position(int pos) { function_token_position_ = pos; }
   int function_token_position() const { return function_token_position_; }
   int start_position() const;
@@ -2605,15 +2607,13 @@ class FunctionLiteral FINAL : public Expression {
   }
 
  protected:
-  FunctionLiteral(Zone* zone, const AstRawString* name,
-                  AstValueFactory* ast_value_factory, Scope* scope,
-                  ZoneList<Statement*>* body, int materialized_literal_count,
-                  int expected_property_count, int handler_count,
-                  int parameter_count, FunctionType function_type,
-                  ParameterFlag has_duplicate_parameters,
-                  IsFunctionFlag is_function,
-                  IsParenthesizedFlag is_parenthesized, FunctionKind kind,
-                  int position)
+  FunctionLiteral(
+      Zone* zone, const AstRawString* name, AstValueFactory* ast_value_factory,
+      Scope* scope, ZoneList<Statement*>* body, int materialized_literal_count,
+      int expected_property_count, int handler_count, int parameter_count,
+      ZoneList<Expression*>* default_values, FunctionType function_type,
+      ParameterFlag has_duplicate_parameters, IsFunctionFlag is_function,
+      IsParenthesizedFlag is_parenthesized, FunctionKind kind, int position)
       : Expression(zone, position),
         raw_name_(name),
         scope_(scope),
@@ -2625,6 +2625,7 @@ class FunctionLiteral FINAL : public Expression {
         expected_property_count_(expected_property_count),
         handler_count_(handler_count),
         parameter_count_(parameter_count),
+        default_values_(default_values),
         function_token_position_(RelocInfo::kNoPosition) {
     bitfield_ = IsExpression::encode(function_type != DECLARATION) |
                 IsAnonymous::encode(function_type == ANONYMOUS_EXPRESSION) |
@@ -2651,6 +2652,7 @@ class FunctionLiteral FINAL : public Expression {
   int expected_property_count_;
   int handler_count_;
   int parameter_count_;
+  ZoneList<Expression*>* default_values_;
   int function_token_position_;
 
   unsigned bitfield_;
@@ -3539,6 +3541,7 @@ class AstNodeFactory FINAL BASE_EMBEDDED {
       const AstRawString* name, AstValueFactory* ast_value_factory,
       Scope* scope, ZoneList<Statement*>* body, int materialized_literal_count,
       int expected_property_count, int handler_count, int parameter_count,
+      ZoneList<Expression*>* default_parameters,
       FunctionLiteral::ParameterFlag has_duplicate_parameters,
       FunctionLiteral::FunctionType function_type,
       FunctionLiteral::IsFunctionFlag is_function,
@@ -3546,9 +3549,9 @@ class AstNodeFactory FINAL BASE_EMBEDDED {
       int position) {
     return new (zone_) FunctionLiteral(
         zone_, name, ast_value_factory, scope, body, materialized_literal_count,
-        expected_property_count, handler_count, parameter_count, function_type,
-        has_duplicate_parameters, is_function, is_parenthesized, kind,
-        position);
+        expected_property_count, handler_count, parameter_count,
+        default_parameters, function_type, has_duplicate_parameters,
+        is_function, is_parenthesized, kind, position);
   }
 
   ClassLiteral* NewClassLiteral(const AstRawString* name, Scope* scope,