Include stacktrace into log messages

This would align behavior in Chrome and the spec.

Related discussions:

- puppeteer/puppeteer#13264
- whatwg/console#203

index.bs

@@ -10854,7 +10854,7 @@ Define the following [=console steps=] with |method|, |args|, and
 
   1. Let |source| be the result of [=get the source=] given [=current Realm Record=].
 
-  1. If |method| is "<code>assert</code>", "<code>error</code>",
+  1. If |method| is "<code>assert</code>", "<code>error</code>", "<code>log</code>",
      "<code>trace</code>", or "<code>warn</code>", let |stack| be the [=current
      stack trace=]. Otherwise let |stack| be null.