fix sdk dir detection on mac the homebrew version of Dart symlinks the SDK, now it can follow links like the dartanalyzer shell script can
fix sdk dir detection on mac
the homebrew version of Dart symlinks the SDK, now it can follow links like the dartanalyzer shell script can

R=sigmund@google.com

Review URL: https://chromereviews.googleplex.com/126007014

dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk