[Form] Removed the "disabled" attribute from the placeholder option in select fields due to problems with the BlackBerry 10 browser
merged branch bschussek/issue8526 (PR #8622)

This PR was merged into the 2.2 branch.

Discussion
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[Form] Removed the "disabled" attribute from the placeholder option in select fields due to problems with the BlackBerry 10 browser

| Q             | A
| ------------- | ---
| Bug fix?      | yes (together with #8623)
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #7678 #8478 #8526
| License       | MIT
| Doc PR        | -

Commits
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97cbb19 [Form] Removed the "disabled" attribute from the placeholder option in select fields due to problems with the BlackBerry 10 browser