Missing or non-existent entity controller class now throws an EntityMalformedException in Drupal 7

entity_get_controller gets the entity controller for an entity type.

Before this change, if the entity controller class was missing or non-existent, the was an error:

Error: Class name must be a valid object or a string in entity_get_controller() (line 8216 of includes/common.inc).

After this change, if the entity controller class is missing or non-existent, the function will throw an EntityMalformedException:

EntityMalformedException: Missing or non-existent controller class on entity of type test. in entity_get_controller().