[parser] Void reporting errors in the presence of unidentifiable errors.

BUG= v8:8372

Change-Id: Ic29847674a1e455a405c4599c01785ee7aefcedc
Reviewed-on: https://chromium-review.googlesource.com/c/1301500
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57032}

src/pending-compilation-error-handler.h

@@ -59,8 +59,14 @@ class PendingCompilationErrorHandler {
 
   Handle<String> FormatErrorMessageForTest(Isolate* isolate) const;
 
-  bool set_unidentifiable_error() { return unidentifiable_error_ = true; }
-  bool clear_unidentifiable_error() { return unidentifiable_error_ = false; }
+  void set_unidentifiable_error() {
+    has_pending_error_ = true;
+    unidentifiable_error_ = true;
+  }
+  void clear_unidentifiable_error() {
+    has_pending_error_ = false;
+    unidentifiable_error_ = false;
+  }
   bool has_error_unidentifiable_by_preparser() const {
     return unidentifiable_error_;
   }