[debugger] step on every assignment in destructuring bind.

src/parsing/parser.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_PARSING_PARSER_H_
 #define V8_PARSING_PARSER_H_
 
 #include "src/allocation.h"
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
@@ skipping 1059 matching lines @@
       ASSIGNMENT,
       ASSIGNMENT_INITIALIZER
     };
 
     PatternContext context() const { return context_; }
     void set_context(PatternContext context) { context_ = context; }
 
     void RecurseIntoSubpattern(AstNode* pattern, Expression* value) {
       Expression* old_value = current_value_;
       current_value_ = value;
+      recursion_level_++;
       pattern->Accept(this);
+      recursion_level_--;
       current_value_ = old_value;
     }
 
     void VisitObjectLiteral(ObjectLiteral* node, Variable** temp_var);
     void VisitArrayLiteral(ArrayLiteral* node, Variable** temp_var);
 
     bool IsBindingContext() const { return IsBindingContext(context_); }
     bool IsInitializerContext() const { return context_ != ASSIGNMENT; }
     bool IsAssignmentContext() const { return IsAssignmentContext(context_); }
     bool IsAssignmentContext(PatternContext c) const;
     bool IsBindingContext(PatternContext c) const;
+    bool IsSubPattern() const { return recursion_level_ > 1; }
     PatternContext SetAssignmentContextIfNeeded(Expression* node);
     PatternContext SetInitializerContextIfNeeded(Expression* node);
 
     Variable* CreateTempVar(Expression* value = nullptr);
 
     AstNodeFactory* factory() const { return parser_->factory(); }
     AstValueFactory* ast_value_factory() const {
       return parser_->ast_value_factory();
     }
     Zone* zone() const { return parser_->zone(); }
     Scope* scope() const { return scope_; }
 
     Scope* scope_;
     Parser* parser_;
     PatternContext context_;
     Expression* pattern_;
     int initializer_position_;
     Block* block_;
     const DeclarationDescriptor* descriptor_;
     ZoneList<const AstRawString*>* names_;
     Expression* current_value_;
+    int recursion_level_;
     bool* ok_;
   };
 
 
   void ParseVariableDeclarations(VariableDeclarationContext var_context,
                                  DeclarationParsingResult* parsing_result,
                                  bool* ok);
   Statement* ParseExpressionOrLabelledStatement(
       ZoneList<const AstRawString*>* labels, bool* ok);
   IfStatement* ParseIfStatement(ZoneList<const AstRawString*>* labels,
@@ skipping 319 matching lines @@
 
 DoExpression* ParserTraits::ParseDoExpression(bool* ok) {
   return parser_->ParseDoExpression(ok);
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_H_