Enable icu_use_data_file on Windows


Set icu_use_data_file_flag to 1 on Windows in common.gypi and make the dependency on icudata conditional on 'icu_use_data_file_flag != 0' in common.gypi, base.gyp and net.gyp

This also requires a change in third_party/icu/icu.gyp
( https://codereview.chromium.org/111723007/ ), which was rolled in by https://codereview.chromium.org/118313004/

BUG=72633
TEST=All windows builds work fine and there's no perf regression (start-up etc).

Review URL: https://codereview.chromium.org/99473012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246387 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246387