Add DumpWithoutCrashing in RendererDidNavigateToExistingPage

This is intended to be reverted after investigating the linked bug.

BUG=688425
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation

Review-Url: https://codereview.chromium.org/2701523004
Cr-Commit-Position: refs/heads/master@{#450900}
void NavigationControllerImpl::ContinuePendingReload() {
  if (pending_reload_ == ReloadType::NONE) {
    NOTREACHED();
  } else {
    Reload(pending_reload_, false);
    pending_reload_ = ReloadType::NONE;
  }
}

void NavigationControllerImpl::ContinuePendingReload() {
  if (pending_reload_ == ReloadType::NONE) {
    NOTREACHED();
  } else {
    Reload(pending_reload_, false);
    pending_reload_ = ReloadType::NONE;
  }
}
