[parsing] Don't validate module if parsing failed.

Otherwise we might come across invalid locations.

Bug: chromium:923675
Change-Id: I0b01ba4b11cc7270744ec438bedb0b8ada2aa29d
Reviewed-on: https://chromium-review.googlesource.com/c/1426126
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59026}

src/parsing/parser.cc

@@ -578,7 +578,8 @@ FunctionLiteral* Parser::DoParseProgram(Isolate* isolate, ParseInfo* info) {
           factory()->NewExpressionStatement(initial_yield, kNoSourcePosition));
 
       ParseModuleItemList(&body);
-      if (!module()->Validate(this->scope()->AsModuleScope(),
+      if (!has_error() &&
+          !module()->Validate(this->scope()->AsModuleScope(),
                               pending_error_handler(), zone())) {
         scanner()->set_parser_error();
       }

test/message/fail/modules-export-illformed-class.js

+// Copyright 2019 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.
+
+// MODULE
+
+export class foo {[]};

test/message/fail/modules-export-illformed-class.out

+*%(basename)s:7: SyntaxError: Unexpected token ]
+export class foo {[]};
+                   ^
+SyntaxError: Unexpected token ]
+