net: replicate r62288 in DnsRRResolver
net: replicate r62288 in DnsRRResolver

When _res is uninitialized, res_nclose may end up closing fd 0.
Test whether it's initialized before closing.

Patch by Jim Deng.

TBR=evanm

Original review URL: http://codereview.chromium.org/3717002

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@62292 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser