[fuzzing] consistently honor --abort-on-stack-overflow.

src/regexp/regexp-parser.cc

Index: src/regexp/regexp-parser.cc
diff --git a/src/regexp/regexp-parser.cc b/src/regexp/regexp-parser.cc
index fd3123f674e3ca74986b945809cd7e439c09dc34..381e0d121ece5f77b823f2811df422e3c02ea845 100644
--- a/src/regexp/regexp-parser.cc
+++ b/src/regexp/regexp-parser.cc
@@ -75,6 +75,7 @@ void RegExpParser::Advance() {
   if (has_next()) {
     StackLimitCheck check(isolate());
     if (check.HasOverflowed()) {
+      if (FLAG_abort_on_stack_overflow) FATAL("Aborting on stack overflow");
       ReportError(CStrVector(
           MessageTemplate::TemplateString(MessageTemplate::kStackOverflow)));
     } else if (zone()->excess_allocation()) {