Re-apply formal argument, arrow function parsing refactors

src/parser.h

Index: src/parser.h
diff --git a/src/parser.h b/src/parser.h
index 8d557aed53eca468795303c536bbd17252890551..0c1f16a3ce31082bd1ec6af1abeab79088100aa4 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -557,6 +557,7 @@ class ParserTraits {
     typedef ObjectLiteral::Property* ObjectLiteralProperty;
     typedef ZoneList<v8::internal::Expression*>* ExpressionList;
     typedef ZoneList<ObjectLiteral::Property*>* PropertyList;
+    typedef const v8::internal::AstRawString* FormalParameter;
     typedef ZoneList<v8::internal::Statement*>* StatementList;
 
     // For constructing objects returned by the traversing functions.
@@ -694,7 +695,6 @@ class ParserTraits {
   static Expression* EmptyExpression() {
     return NULL;
   }
-  static Expression* EmptyArrowParamList() { return NULL; }
   static Literal* EmptyLiteral() {
     return NULL;
   }
@@ -705,6 +705,7 @@ class ParserTraits {
   static ZoneList<Expression*>* NullExpressionList() {
     return NULL;
   }
+  static const AstRawString* EmptyFormalParameter() { return NULL; }
 
   // Non-NULL empty string.
   V8_INLINE const AstRawString* EmptyIdentifierString();
@@ -743,11 +744,24 @@ class ParserTraits {
   V8_INLINE Scope* NewScope(Scope* parent_scope, ScopeType scope_type,
                             FunctionKind kind = kNormalFunction);
 
-  // Utility functions
-  int DeclareArrowParametersFromExpression(Expression* expression, Scope* scope,
-                                           Scanner::Location* undefined_loc,
-                                           Scanner::Location* dupe_loc,
-                                           bool* ok);
+  void DeclareFormalParameter(Scope* scope, const AstRawString* name,
+                              bool is_rest) {
+    Variable* var = scope->DeclareParameter(name, VAR, is_rest);
+    if (is_sloppy(scope->language_mode())) {
+      // TODO(sigurds) Mark every parameter as maybe assigned. This is a
+      // conservative approximation necessary to account for parameters
+      // that are assigned via the arguments array.
+      var->set_maybe_assigned();
+    }
+  }
+
+  void DeclareArrowFunctionParameters(Scope* scope, Expression* expr,
+                                      const Scanner::Location& params_loc,
+                                      FormalParameterErrorLocations* error_locs,
+                                      bool* ok);
+  void ParseArrowFunctionFormalParameters(
+      Scope* scope, Expression* params, const Scanner::Location& params_loc,
+      FormalParameterErrorLocations* error_locs, bool* is_rest, bool* ok);
 
   // Temporary glue; these functions will move to ParserBase.
   Expression* ParseV8Intrinsic(bool* ok);
@@ -1045,8 +1059,6 @@ class Parser : public ParserBase<ParserTraits> {
   ScriptCompiler::CompileOptions compile_options_;
   ParseData* cached_parse_data_;
 
-  bool parsing_lazy_arrow_parameters_;  // for lazily parsed arrow functions.
-
   PendingCompilationErrorHandler pending_error_handler_;
 
   // Other information which will be stored in Parser and moved to Isolate after