Add msvs_emulation expansion for $(TargetName) and $(TargetDir)

* $(TargetDir) is equivalent to $(OutDir)
* $(TargetName) logic is taken from the logic that sets 'TargetName' in
  generators/msvs.py

R=scottmg@chromium.org
BUG=

Review URL: https://codereview.chromium.org/19660003

git-svn-id: http://gyp.googlecode.com/svn/trunk@1682 78cadc50-ecff-11dd-a971-7dbc132099af