Don't use formatted display titles to generate URIs

Use options.page.title rather than options.heading to generate URIs, because
the latter may contain display formatting. Until recently it happened not to,
so the URIs worked anyway. But commit c3e482cd5620801a37bb022cac141e83036a1e6a
wrapped some titles in span tags for display purposes, which then leaked into
the URIs, breaking the "Read this page in full" links in the Nearby feature.

Bug: 60351
Change-Id: I0a29f7369d2c98e6890a18e654cf462c0dea10be