[parser] Cook invalid template literals if we've thrown

Otherwise we may look into the invalid string literal later.

Bug: chromium:903527
Change-Id: Ieeb3807bd05e532224e04a59878f5dac24e19579
Reviewed-on: https://chromium-review.googlesource.com/c/1329691
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57423}

src/ast/ast.h

@@ -3084,6 +3084,7 @@ class AstNodeFactory final {
   }
 
   Literal* NewStringLiteral(const AstRawString* string, int pos) {
+    DCHECK_NOT_NULL(string);
     return new (zone_) Literal(string, pos);
   }
 

src/parsing/parser-base.h

@@ -782,7 +782,7 @@ class ParserBase {
       impl()->ReportMessageAt(scanner()->invalid_template_escape_location(),
                               scanner()->invalid_template_escape_message());
     }
-    return false;
+    return should_throw;
   }
 
   void CheckDestructuringElement(ExpressionT element, int beg_pos, int end_pos);

test/mjsunit/regress/regress-903527.js

+// 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("e*!`\\2`", SyntaxError)