[parsing] Fix maybe-assigned flag in some cases.

src/ast/ast.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_AST_H_
 #define V8_AST_AST_H_
 
 #include "src/ast/ast-types.h"
 #include "src/ast/ast-value-factory.h"
 #include "src/ast/modules.h"
@@ skipping 1616 matching lines @@
   void set_var(Variable* v) {
     DCHECK(!is_resolved());
     DCHECK_NOT_NULL(v);
     var_ = v;
   }
 
   bool is_this() const { return IsThisField::decode(bit_field_); }
 
   bool is_assigned() const { return IsAssignedField::decode(bit_field_); }
   void set_is_assigned() {
-    DCHECK(!is_resolved());
     bit_field_ = IsAssignedField::update(bit_field_, true);
+    if (is_resolved()) {
+      var()->set_maybe_assigned();
+    }
   }
 
   bool is_resolved() const { return IsResolvedField::decode(bit_field_); }
   void set_is_resolved() {
     bit_field_ = IsResolvedField::update(bit_field_, true);
   }
 
   bool is_new_target() const { return IsNewTargetField::decode(bit_field_); }
   void set_is_new_target() {
     bit_field_ = IsNewTargetField::update(bit_field_, true);
@@ skipping 1799 matching lines @@
   RewritableExpression* NewRewritableExpression(Expression* expression) {
     DCHECK_NOT_NULL(expression);
     return new (zone_) RewritableExpression(expression);
   }
 
   Assignment* NewAssignment(Token::Value op,
                             Expression* target,
                             Expression* value,
                             int pos) {
     DCHECK(Token::IsAssignmentOp(op));
+
+    if (op != Token::INIT && target->IsVariableProxy()) {
+      target->AsVariableProxy()->set_is_assigned();
+    }
+
     Assignment* assign = new (zone_) Assignment(op, target, value, pos);
     if (assign->is_compound()) {
-      DCHECK(Token::IsAssignmentOp(op));
       assign->binary_operation_ =
           NewBinaryOperation(assign->binary_op(), target, value, pos + 1);
     }
     return assign;
   }
 
   Yield* NewYield(Expression* generator_object, Expression* expression, int pos,
                   Yield::OnException on_exception) {
     if (!expression) expression = NewUndefinedLiteral(pos);
     return new (zone_) Yield(generator_object, expression, pos, on_exception);
@@ skipping 157 matching lines @@
                                     : NULL;                                   \
   }
 AST_NODE_LIST(DECLARE_NODE_FUNCTIONS)
 #undef DECLARE_NODE_FUNCTIONS
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_AST_H_