[parser] If we re-parse after preparsing, reset stack overflow too

The bug was that PreParser detected a stack overflow and an unidentifiable
error, and we tried to re-parse the same code. However, the stack overflow flag
was still set, and that messed up error handling in the Parser.

BUG=chromium:899495

Change-Id: Icdef74bdb8be252d75f245e243e1303ffb822ce2
Reviewed-on: https://chromium-review.googlesource.com/c/1304316Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57082}

src/pending-compilation-error-handler.h

@@ -66,6 +66,7 @@ class PendingCompilationErrorHandler {
   void clear_unidentifiable_error() {
     has_pending_error_ = false;
     unidentifiable_error_ = false;
+    stack_overflow_ = false;
   }
   bool has_error_unidentifiable_by_preparser() const {
     return unidentifiable_error_;