Ignore new dart_tool pub cache directory

pq · pq · commit 6d2fcab13f2a · 2018-03-10T14:54:49.000-08:00
See: dart-lang/sdk#32030
diff --git a/.gitignore b/.gitignore
@@ -6,7 +6,7 @@ packages
 .DS_Store
 .packages
 pubspec.lock
-.pub/
+.dart_tool
 .idea/
 .vscode/
 material-design-icons/
