[parser] Use scope instead of explicit discarding of classifier

Change-Id: I8f5da41d11df5fce7df4f7757717fb165a6043d9
Reviewed-on: https://chromium-review.googlesource.com/c/1288391Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56760}

src/parsing/expression-classifier.h

@@ -222,9 +222,7 @@ class ExpressionClassifierErrorTracker
     reported_errors_begin_ = reported_errors_end_ = reported_errors_->length();
   }
 
-  ~ExpressionClassifierErrorTracker() override { Discard(); }
-
-  V8_INLINE void Discard() {
+  ~ExpressionClassifierErrorTracker() override {
     if (reported_errors_end_ == reported_errors_->length()) {
       reported_errors_->Rewind(reported_errors_begin_);
       reported_errors_end_ = reported_errors_begin_;
@@ -365,8 +363,6 @@ class ExpressionClassifierEmptyErrorTracker
   explicit ExpressionClassifierEmptyErrorTracker(typename Types::Base* base)
       : BaseClassType(base) {}
 
-  V8_INLINE void Discard() {}
-
  protected:
   V8_INLINE const Error& reported_error(ErrorKind kind) const {
     static Error none;

src/parsing/parser-base.h

@@ -1461,14 +1461,6 @@ class ParserBase {
                        ExpressionClassifier::LetPatternProduction));
   }
 
-  // Pops and discards the classifier that is on top of the stack
-  // without accumulating.
-  V8_INLINE void DiscardExpressionClassifier() {
-    DCHECK_NOT_NULL(classifier_);
-    classifier_->Discard();
-    classifier_ = classifier_->previous();
-  }
-
   // Accumulate errors that can be arbitrarily deep in an expression.
   // These correspond to the ECMAScript spec's 'Contains' operation
   // on productions. This includes:
@@ -3650,14 +3642,14 @@ void ParserBase<Impl>::ParseFormalParameter(FormalParametersT* parameters,
       *ok = false;
       return;
     }
-    ExpressionClassifier init_classifier(this);
-    initializer = ParseAssignmentExpression(true, CHECK_OK_CUSTOM(Void));
-    ValidateExpression(CHECK_OK_CUSTOM(Void));
-    ValidateFormalParameterInitializer(CHECK_OK_CUSTOM(Void));
-    parameters->is_simple = false;
-    DiscardExpressionClassifier();
+    {
+      ExpressionClassifier init_classifier(this);
+      initializer = ParseAssignmentExpression(true, CHECK_OK_CUSTOM(Void));
+      ValidateExpression(CHECK_OK_CUSTOM(Void));
+      ValidateFormalParameterInitializer(CHECK_OK_CUSTOM(Void));
+      parameters->is_simple = false;
+    }
     classifier()->RecordNonSimpleParameter();
-
     impl()->SetFunctionNameFromIdentifierRef(initializer, pattern);
   }