[parser] parenthesized Literals are not valid AssignmentPatterns

src/parsing/preparser.h

Index: src/parsing/preparser.h
diff --git a/src/parsing/preparser.h b/src/parsing/preparser.h
index 9253ad5e518f93b9cfc08393a475912eb6377e85..41d5ab8513626776ea3738db8ca78c5301b3e81f 100644
--- a/src/parsing/preparser.h
+++ b/src/parsing/preparser.h
@@ -279,6 +279,12 @@ class PreParserExpression {
   int position() const { return RelocInfo::kNoPosition; }
   void set_function_token_position(int position) {}
 
+  // Parenthesized expressions in the form `( Expression )`.
+  void set_is_parenthesized() {
+    code_ = ParenthesizedField::update(code_, true);
+  }
+  bool is_parenthesized() const { return ParenthesizedField::decode(code_); }
+
  private:
   enum Type {
     kExpression,
@@ -306,6 +312,13 @@ class PreParserExpression {
   // The first three bits are for the Type.
   typedef BitField<Type, 0, 3> TypeField;
 
+  // The high order bit applies only to nodes which would inherit from the
+  // Expression ASTNode --- This is by necessity, due to the fact that
+  // Expression nodes may be represented as multiple Types, not exclusively
+  // through kExpression.
+  // TODO(caitp, adamk): clean up PreParserExpression bitfields.
+  typedef BitField<bool, 31, 1> ParenthesizedField;
+
   // The rest of the bits are interpreted depending on the value
   // of the Type field, so they can share the storage.
   typedef BitField<ExpressionType, TypeField::kNext, 3> ExpressionTypeField;