Fix WKBasedNavigationManagerImpl::CommitPendingItem for back forward navigations.

The change mirrors LegacyNavigationManagerImpl::CommitPendingItem
implementation by calling CommitPendingItem() if pending item index
is not -1.

Bug: 899827
Change-Id: Iab6459b6673e2a2d0e413728de4b870affb30956
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1526629
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Commit-Queue: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#641756}
1 file changed