Reminder: Remove PDO workaround code when two core bugs are closed.

The committed patch to #1084268: Exception: Invalid field name given. in FieldCollectionItemEntity worked around two core bugs. This ticket is to remind us to remove the workaround once the core issues are resolved.

Here is the current comments describing the workaround in the code:

// Workaround issues http://drupal.org/node/1084268 and
// http://drupal.org/node/1264440:
// Check if the required property is set before checking for the field's
// type. If the property is not set, we are hiting a PDO or a core's bug.
// FIXME: Remove when #1264440 is fixed and the required PHP version is
//  properly identified and documented in the module documentation.