[parser] Only clear invalid template escape messages if we have them

Change-Id: I9925db0d74ef96bf91ea261f275e37c10908c9ef
Reviewed-on: https://chromium-review.googlesource.com/c/1335695
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57507}

src/parsing/parser-base.h

@@ -773,15 +773,14 @@ class ParserBase {
   inline bool CheckTemplateEscapes(bool should_throw) {
     DCHECK(scanner()->current_token() == Token::TEMPLATE_SPAN ||
            scanner()->current_token() == Token::TEMPLATE_TAIL);
-    if (!scanner()->has_invalid_template_escape()) {
-      return true;
-    }
+    if (!scanner()->has_invalid_template_escape()) return true;
 
     // Handle error case(s)
     if (should_throw) {
       impl()->ReportMessageAt(scanner()->invalid_template_escape_location(),
                               scanner()->invalid_template_escape_message());
     }
+    scanner()->clear_invalid_template_escape_message();
     return should_throw;
   }
 

src/parsing/scanner-inl.h

@@ -501,8 +501,6 @@ V8_INLINE Token::Value Scanner::ScanSingleToken() {
 void Scanner::Scan(TokenDesc* next_desc) {
   DCHECK_EQ(next_desc, &next());
 
-  next_desc->invalid_template_escape_message = MessageTemplate::kNone;
-
   next_desc->token = ScanSingleToken();
   DCHECK_IMPLIES(has_parser_error(), next_desc->token == Token::ILLEGAL);
   next_desc->location.end_pos = source_pos();

src/parsing/scanner.h

@@ -296,6 +296,12 @@ class Scanner {
     DCHECK(has_invalid_template_escape());
     return current().invalid_template_escape_message;
   }
+
+  void clear_invalid_template_escape_message() {
+    DCHECK(has_invalid_template_escape());
+    current_->invalid_template_escape_message = MessageTemplate::kNone;
+  }
+
   Location invalid_template_escape_location() const {
     DCHECK(has_invalid_template_escape());
     return current().invalid_template_escape_location;