[parsing] Be less pessimistic about maybe_assigned of parameters.

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/ast/ast.h"
 #include "src/ast/scopes.h"
 #include "src/base/compiler-specific.h"
@@ skipping 1056 matching lines @@
       if (!is_simple) scope->SetHasNonSimpleParameters();
       bool is_optional = parameter->initializer != nullptr;
       Variable* var =
           scope->DeclareParameter(name, mode, is_optional, parameter->is_rest,
                                   &is_duplicate, ast_value_factory());
       if (is_duplicate &&
           classifier()->is_valid_formal_parameter_list_without_duplicates()) {
         classifier()->RecordDuplicateFormalParameterError(
             scanner()->location());
       }
-      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 DeclareArrowFunctionFormalParameters(ParserFormalParameters* parameters,
                                             Expression* params,
                                             const Scanner::Location& params_loc,
                                             Scanner::Location* duplicate_loc,
                                             bool* ok);
 
   void ReindexLiterals(const ParserFormalParameters& parameters);
@@ skipping 95 matching lines @@
 
  private:
   ParserTarget** variable_;
   ParserTarget* previous_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_H_