Cleaned up Crankshaft pipeline a bit.

Two tiny changes:

  * Some phases were missing an HPhase, which was added, so we can now see all
    phases in the visualizer output.

  * Consistently test commandline flags directly in the pipeline, making it
    clearer which parts are optional and which are not.

R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/15074005

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14615 ce2b1a6d-e550-0410-aec6-3dcde31c8c00