Support an executable in a symlinked directory.

lib/cli_util.dart

Index: lib/cli_util.dart
diff --git a/lib/cli_util.dart b/lib/cli_util.dart
index 683bef7e2629ff0355df01c55f1b4acadcd13d0f..aff2c6799978a1445c485fdc512e0ae9fdfe69e4 100644
--- a/lib/cli_util.dart
+++ b/lib/cli_util.dart
@@ -6,6 +6,7 @@ library cli_util;
 
 import 'dart:io';
 
+import 'package:path/path.dart' as p;
 import 'package:which/which.dart';
 
 /// Return the path to the current Dart SDK. This will return `null` if we are
@@ -45,6 +46,12 @@ Directory getSdkDir([List<String> cliArgs]) {
       executable = link.resolveSymbolicLinksSync();
     }
 
+    Link parentLink = new Link(p.dirname(executable));
+    if (parentLink.existsSync()) {
+      executable = p.join(
+          parentLink.resolveSymbolicLinksSync(), p.basename(executable));
+    }
+
     File dartVm = new File(executable);
     Directory dir = dartVm.parent.parent;
     if (_isSdkDir(dir)) return dir;