Improve exception error messages in Source/core/editing/markup.cpp.

BUG=270033

Review URL: https://codereview.chromium.org/26234005

git-svn-id: svn://svn.chromium.org/blink/trunk@160201 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Making multiple select element RTL direction aware

BUG=85833

Review URL: https://codereview.chromium.org/31393004

git-svn-id: svn://svn.chromium.org/blink/trunk@160202 bbb929c8-8fbe-4397-9dbb-9b2b20218538