Added support for injecting HttpFoundation's RequestStack in ServerParams
feature #10912 [Form] Added support for injecting HttpFoundation's Request in ServerParams for the Validator extension (csarrazi)

This PR was merged into the 2.4-dev branch.

Discussion
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[Form] Added support for injecting HttpFoundation's Request in ServerParams for the Validator extension

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #10009
| License       | MIT
| Doc PR        | -

The Request object should be injected in the ```ServerParams``` object before using it in the extension, if one wishes to use Symfony2's ```Request``` to fetch the server parameters.

Commits
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86f9cb9 Added support for injecting HttpFoundation's RequestStack in ServerParams