Rescope arrow-function parameter lists by moving the delta to the parameter scope

src/ast/scopes.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_AST_SCOPES_H_
 #define V8_AST_SCOPES_H_
 
 #include "src/ast/ast.h"
 #include "src/base/hashmap.h"
 #include "src/globals.h"
@@ skipping 74 matching lines @@
 // Script variable.
 
 class Scope: public ZoneObject {
  public:
   // ---------------------------------------------------------------------------
   // Construction
 
   Scope(Zone* zone, Scope* outer_scope, ScopeType scope_type,
         FunctionKind function_kind = kNormalFunction);
 
+  class Snapshot final BASE_EMBEDDED {
+   public:
+    explicit Snapshot(Scope* scope)
+        : outer_scope_(scope),
+          top_inner_scope_(scope->inner_scope_),
+          top_unresolved_(scope->unresolved_),
+          top_temp_(scope->ClosureScope()->temps_.length()) {}
+
+    void Reparent(Scope* new_parent) const;
+
+   private:
+    Scope* outer_scope_;
+    Scope* top_inner_scope_;
+    VariableProxy* top_unresolved_;
+    int top_temp_;
+  };
+
   // Compute top scope and allocate variables. For lazy compilation the top
   // scope only contains the single lazily compiled function, so this
   // doesn't re-allocate variables repeatedly.
   static bool Analyze(ParseInfo* info);
 
   static Scope* DeserializeScopeChain(Isolate* isolate, Zone* zone,
                                       Context* context, Scope* script_scope,
                                       AstValueFactory* ast_value_factory);
 
   // The scope name is only used for printing/debugging.
@@ skipping 732 matching lines @@
 
   void SetDefaults();
 
   PendingCompilationErrorHandler pending_error_handler_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_SCOPES_H_