Reland of Preparse functions in the scope that was created when parsing of the function was started

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/base/hashmap.h"
 #include "src/globals.h"
 #include "src/objects.h"
@@ skipping 790 matching lines @@
   }
 
 #ifdef DEBUG
   void PrintParameters();
 #endif
 
   void AllocateLocals();
   void AllocateParameterLocals();
   void AllocateReceiver();
 
+  void ResetAfterPreparsing() {
+    // Reset all non-trivial members.
+    decls_.Clear();
+    locals_.Clear();
+    params_.Clear();
+    sloppy_block_function_map_.Clear();
+    variables_.Clear();
+    // Make sure we won't walk the scope tree from here on.
+    inner_scope_ = nullptr;
+    // Make sure we won't try to allocate the rest parameter. {params_} was
+    // cleared above.
+    has_rest_ = false;
+  }
+
  private:
   void AllocateParameter(Variable* var, int index);
 
   // Resolve and fill in the allocation information for all variables
   // in this scopes. Must be called *after* all scopes have been
   // processed (parsed) to ensure that unresolved variables can be
   // resolved properly.
   //
   // In the case of code compiled and run using 'eval', the context
   // parameter is the context in which eval was called.  In all other
@@ skipping 58 matching lines @@
   void AllocateModuleVariables();
 
  private:
   ModuleDescriptor* module_descriptor_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_SCOPES_H_