Improve exception messages for detached Range objects.

Calling a variety of methods on detached Range objects will throw
InvalidStateError. This patch adds some detail to the exception message
in the hopes of informing developers about their errors.

BUG=270033

Review URL: https://chromiumcodereview.appspot.com/23964014

git-svn-id: svn://svn.chromium.org/blink/trunk@158268 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: Try to show JSON preview for all application/json responses.

BUG=296853
R=pfeldman

Review URL: https://chromiumcodereview.appspot.com/24302006

git-svn-id: svn://svn.chromium.org/blink/trunk@158269 bbb929c8-8fbe-4397-9dbb-9b2b20218538