Revert r1745: "Add an option to prune targets"

The test does not work on xcode.

BUG=
R=thakis@chromium.org

Review URL: https://codereview.chromium.org/25398003

git-svn-id: http://gyp.googlecode.com/svn/trunk@1746 78cadc50-ecff-11dd-a971-7dbc132099af
11 files changed