CaptivePortalLogin ignores some ssl errors.

This patch changes the ssl error handler of the captive portal login
activity to ignore errors for resources coming from a different hostname
that the top-level page currently loading.

This allows logging into misconfigured portals that incorrectly bans ssl
to some hostnames necessary for loading their portal login pages.

Bug: 62332137
Test: manually tested with captive portal entwork.

(cherry pick from commit 22542ed4 which
was skipped from merging into stage-aosp-master)

Change-Id: Iff025d68b824eac2c30b9656fd2494338eb07eb3