[parser] Don't re-preparse when trying to find an unidentifiable error

Bug: chromium:907669
Change-Id: I7633780b1f3a1a290593818a3e558c5a1bb81502
Reviewed-on: https://chromium-review.googlesource.com/c/1347486
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57735}

src/parsing/parser-base.h

@@ -1717,8 +1717,11 @@ ParserBase<Impl>::ParsePrimaryExpression() {
       if (Check(Token::RPAREN)) {
         // ()=>x.  The continuation that consumes the => is in
         // ParseAssignmentExpression.
-        if (peek() != Token::ARROW) ReportUnexpectedToken(Token::RPAREN);
-        next_arrow_formals_parenthesized_ = true;
+        if (peek() == Token::ARROW) {
+          next_arrow_formals_parenthesized_ = true;
+        } else {
+          ReportUnexpectedToken(Token::RPAREN);
+        }
         return factory()->NewEmptyParentheses(beg_pos);
       }
       // Heuristically try to detect immediately called functions before

src/parsing/parser.cc

@@ -2710,6 +2710,10 @@ bool Parser::SkipFunction(
     // Propagate stack overflow.
     set_stack_overflow();
   } else if (pending_error_handler()->has_error_unidentifiable_by_preparser()) {
+    // Make sure we don't re-preparse inner functions of the aborted function.
+    // The error might be in an inner function.
+    allow_lazy_ = false;
+    mode_ = PARSE_EAGERLY;
     DCHECK(!pending_error_handler()->stack_overflow());
     // If we encounter an error that the preparser can not identify we reset to
     // the state before preparsing. The caller may then fully parse the function

test/mjsunit/regress/regress-907669.js

@@ -0,0 +1,5 @@
+// Copyright 2018 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+assertThrows("function f() { function g() { (); ", SyntaxError);