Stop using urllib.urlretrieve() directly.

Stop using urllib.urlretrieve() directly.

Using urllib for SSL connections when behind a proxy is known to be
broken, so apply the same fix from depot_tools r149742 and use a wrapper
around urllib2 instead.

R=jkummerow@chromium.org
TEST=run test262 behind corporate proxy

Review URL: https://codereview.chromium.org/297663003

Patch from Raphael Kubo da Costa <raphael.kubo.da.costa@intel.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21402 ce2b1a6d-e550-0410-aec6-3dcde31c8c00