[parser] Updated the Error Message for Unparenthesized Exponentiation Expression

-5**2 now produces
SyntaxError: Unary operator used immediately before exponentiation expression.
Parenthesis must be used to disambiguate operator precedence.

Bug: v8:6894
Change-Id: I89dd034ff90ee1a49ba61e0c613da534fbf8b41b
Reviewed-on: https://chromium-review.googlesource.com/c/1418592Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Suraj Sharma <surshar@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#59011}

src/message-template.h

@@ -481,6 +481,9 @@ namespace internal {
   T(UnexpectedNewTarget, "new.target expression is not allowed here")          \
   T(UnexpectedTemplateString, "Unexpected template string")                    \
   T(UnexpectedToken, "Unexpected token %")                                     \
+  T(UnexpectedTokenUnaryExponentiation,                                        \
+    "Unary operator used immediately before exponentiation expression. "       \
+    "Parenthesis must be used to disambiguate operator precedence")            \
   T(UnexpectedTokenIdentifier, "Unexpected identifier")                        \
   T(UnexpectedTokenNumber, "Unexpected number")                                \
   T(UnexpectedTokenString, "Unexpected string")                                \

src/parsing/parser-base.h

@@ -2856,7 +2856,9 @@ ParserBase<Impl>::ParseUnaryOrPrefixExpression() {
     }
 
     if (peek() == Token::EXP) {
-      ReportUnexpectedToken(Next());
+      impl()->ReportMessageAt(
+          Scanner::Location(pos, peek_end_position()),
+          MessageTemplate::kUnexpectedTokenUnaryExponentiation);
       return impl()->FailureExpression();
     }
 

test/message/fail/unparenthesized-exponentiation-expression.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.
+//
+//
+
+-5**2

test/message/fail/unparenthesized-exponentiation-expression.out

+*%(basename)s:7: SyntaxError: Unary operator used immediately before exponentiation expression. Parenthesis must be used to disambiguate operator precedence
+-5**2
+^^^^
+SyntaxError: Unary operator used immediately before exponentiation expression. Parenthesis must be used to disambiguate operator precedence