Revert r92977 partially to fix a certificate verification regression

      on Windows.

We still need X509Certificate::cert_store().  Make it a leaky lazy
instance.

R=rsleevi@chromium.org,rvargas@chromium.org
BUG=89899,49377
TEST=Visit https://bugs.webkit.org/show_bug.cgi?id=64580 on Windows.
Should not get the untrusted certificate error.

Review URL: http://codereview.chromium.org/7473009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@93338 0039d316-1c4b-4281-b951-d872f2087c98