Make compilers agree on source position of thrown errors.

test/message/regress/regress-3995.out

Index: test/message/regress/regress-3995.out
diff --git a/test/message/unterminated-arg-list.out b/test/message/regress/regress-3995.out
similarity index 57%
copy from test/message/unterminated-arg-list.out
copy to test/message/regress/regress-3995.out
index 5be2b3d90c28dffc0382a5463219719ecd7cb887..e4f5b31d1f4b0979ac1b65f6a878a6115611cddd 100644
--- a/test/message/unterminated-arg-list.out
+++ b/test/message/regress/regress-3995.out
@@ -2,7 +2,9 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-*%(basename)s:7: SyntaxError: missing ) after argument list
-}
-^
-SyntaxError: missing ) after argument list
+*%(basename)s:6: Error: boom
+  throw new Error("boom");
+  ^
+Error: boom
+    at *%(basename)s:6:9
+    at *%(basename)s:7:3