[es8] Throw SyntaxError when tail call expressions occur in non-strict mode.

src/parsing/parser-base.h

Index: src/parsing/parser-base.h
diff --git a/src/parsing/parser-base.h b/src/parsing/parser-base.h
index 484d4b977e04c66bd26d3b42d860e00195fd6802..89b5b10da965e0068fbfc66c42a30c2c4fd3e4ba 100644
--- a/src/parsing/parser-base.h
+++ b/src/parsing/parser-base.h
@@ -2228,6 +2228,17 @@ ParserBase<Traits>::ParseTailCallExpression(ExpressionClassifier* classifier,
   CheckNoTailCallExpressions(classifier, CHECK_OK);
 
   Scanner::Location loc(pos, scanner()->location().end_pos);
+  if (!expression->IsCall()) {
+    Scanner::Location sub_loc(sub_expression_pos, loc.end_pos);
+    ReportMessageAt(sub_loc, MessageTemplate::kUnexpectedInsideTailCall);
+    *ok = false;
+    return Traits::EmptyExpression();
+  }
+  if (!is_strict(language_mode())) {
+    ReportMessageAt(loc, MessageTemplate::kUnexpectedSloppyTailCall);
+    *ok = false;
+    return Traits::EmptyExpression();
+  }
   ReturnExprContext return_expr_context =
       function_state_->return_expr_context();
   if (return_expr_context != ReturnExprContext::kInsideValidReturnStatement) {
@@ -2250,12 +2261,6 @@ ParserBase<Traits>::ParseTailCallExpression(ExpressionClassifier* classifier,
     *ok = false;
     return Traits::EmptyExpression();
   }
-  if (!expression->IsCall()) {
-    Scanner::Location sub_loc(sub_expression_pos, loc.end_pos);
-    ReportMessageAt(sub_loc, MessageTemplate::kUnexpectedInsideTailCall);
-    *ok = false;
-    return Traits::EmptyExpression();
-  }
   classifier->RecordTailCallExpressionError(
       loc, MessageTemplate::kUnexpectedTailCall);
   function_state_->AddExpressionInTailPosition(expression, loc);