Added hardcoded maxlength attributes on the author, author_email, author_url, and comment_field input markup. These can be modified via the comment_form_defaults filter. Added logic in wp_handle_comment_submission() to return a WP_Error when the comment_author, comment_author_url, or comment_content values exceed the max length of their columns. Introduces wp_get_comment_column_max_length() which returns the max column length for a given column name, and is filterable. Unit tests included for the error conditions in wp_handle_comment_submission()
Fixes#10377.
Props westonruter rachelbaker.
git-svn-id: https://develop.svn.wordpress.org/trunk@36272 602fd350-edb4-49c9-b593-d223f7449a82
0e85f45cb4