Revert "Disable [FormsTestCase testRepostFormAfterReload]."

This reverts commit d0f90e82.

Reason for revert: Culprit CL which broke the test has been reverted

Original change's description:
> Disable [FormsTestCase testRepostFormAfterReload].
> 
> TBR=eugenebut@chromium.org
> 
> Bug: 968296
> Change-Id: I54cead2d459a678c6e865ace2ecc42559ebbb7b5
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1635293
> Reviewed-by: Mike Dougherty <michaeldo@chromium.org>
> Commit-Queue: Mike Dougherty <michaeldo@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#664562}

TBR=eugenebut@chromium.org,michaeldo@chromium.org

Change-Id: I5b9a7999591603ca7853df9a5087c991007970e8
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 968296
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1637409Reviewed-by: Eugene But <eugenebut@chromium.org>
Commit-Queue: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#664761}

ios/chrome/browser/web/forms_egtest.mm

@@ -206,11 +206,6 @@ id<GREYMatcher> ResendPostButtonMatcher() {
 
 // Tests that a POST followed by reloading the destination page resends data.
 - (void)testRepostFormAfterReload {
-  if (web::GetWebClient()->IsSlimNavigationManagerEnabled()) {
-    // TODO(crbug.com/968296): Re-enable this test.
-    EARL_GREY_TEST_DISABLED(@"Test disabled with Slim Navigation.");
-  }
-
   [self setUpFormTestSimpleHttpServer];
   const GURL destinationURL = GetDestinationUrl();