[Form] Check if IntlDateFormatter constructor returned a valid object before using it
[Process] Reduce I/O load on Windows platform
Optimize assertLocale regexp
minor #11441 [Translator] Optimize assertLocale regexp (Jérémy Derussé)

This PR was merged into the 2.3 branch.

Discussion
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[Translator] Optimize assertLocale regexp

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

Optimize regexp by remove unused variable and using anchored regex.
Thanks @Tobion

Commits
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537c39b Optimize assertLocale regexp
bug #11342 [2.3][Form] Check if IntlDateFormatter constructor returned a valid object before using it (romainneutron)

This PR was merged into the 2.3 branch.

Discussion
----------

[2.3][Form] Check if IntlDateFormatter constructor returned a valid object before using it

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT

`IntlDateFormatter` constructor [may return false](http://www.php.net/manual/en/intldateformatter.create.php#refsect1-intldateformatter.create-returnvalues). This patches avoids fatal errors in these cases

This PR replaces #11334

Commits
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ebf967d [Form] Check if IntlDateFormatter constructor returned a valid object before using it
bug #11120 [2.3][Process] Reduce I/O load on Windows platform (romainneutron)

This PR was merged into the 2.3 branch.

Discussion
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[2.3][Process] Reduce I/O load on Windows platform

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT

When using file handles, no `stream_select` call is done.
On linux platforms, `stream_select` introduce a sleep as it has 0.2s timeout, there is no such pause on Windows, producing lot's of disk I/Os when reading file handles

Commits
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ff0bb01 [Process] Reduce I/O load on Windows platform