Revert "Fix None target type with Ninja build."

This reverts r1883, which seems to be causing gyp-win32 bot failures on
test\ninja\solibs_avoid_relinking\gyptest-solibs-avoid-relinking.py and
test\win\gyptest-link-restat-importlib.py.

BUG=
TBR=etienneb@chromium.org,scottmg@chromium.org

Review URL: https://codereview.chromium.org/230633002

git-svn-id: http://gyp.googlecode.com/svn/trunk@1892 78cadc50-ecff-11dd-a971-7dbc132099af