The `*_label' fields were not being properly set because they were being
considered just as every other expanded field, which is subject to other
considerations to ensure that we do not overwrite user data. Label fields,
on the other hand, _must_ always be set whenever the value changes, and are
_not_ modifiable by the user.
This codifies that `_label' assumption that I would like removed in the
future, but time does not permit that sort of refactoring right
now. Ideally, labels would be treated generically like any other expanded
field and have an attribute set of them that would change their expansion
behavior.
* src/client/dapi/DataApiMediator.js (_updateFieldData): Pass label field id
to `_populateWithMap'.
(_populateWithMap): Use it to always populate the label field when the key
matches, ignoring the other expansion criteria that would inhibit it.
* test/client/dapi/DataApiMediatorTest.js: Update test accordingly.
* src/dapi/DataApiManager.js (triggerFieldUpdate): Provide id to
`_genUiFieldData'.
(_genUiFieldData)[label_id]: New field. Return it as part of the return
object's `label_id' field.
DEV-4077
6b3ab89e77