Include stack trace to error message when constructing a new Error with another Error as argument.

src/messages.js

Index: src/messages.js
diff --git a/src/messages.js b/src/messages.js
index cd4add4bcba5fe773f1ff848844bf082e6f6abb3..2edf2f21565a064d74f7dd909585afab28a35abb 100644
--- a/src/messages.js
+++ b/src/messages.js
@@ -1137,10 +1137,11 @@ function SetUpError() {
               return FormatMessage(%NewMessageObject(obj.type, obj.arguments));
           });
         } else if (!IS_UNDEFINED(m)) {
-          %IgnoreAttributesAndSetProperty(this,
-                                          'message',
-                                          ToString(m),
-                                          DONT_ENUM);
+          %IgnoreAttributesAndSetProperty(
+              this,
+              'message',
+              (m instanceof $Error) ? m.stack : ToString(m),
+              DONT_ENUM);
         }
         captureStackTrace(this, f);
       } else {