don't create project if exists

R=scheglov@google.com

Review URL: https://codereview.chromium.org//762333003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@42126 260f80e4-7a28-3924-810f-c04153c831b5
fixes for using analysis server in plugins

R=scheglov@google.com

Review URL: https://codereview.chromium.org//764033003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@42127 260f80e4-7a28-3924-810f-c04153c831b5