Delete .gitignore

-# See https://www.dartlang.org/guides/libraries/private-files
-
-# Files and directories created by pub
-.dart_tool/
-.packages
-build/
-# If you're building an application, you may want to check-in your pubspec.lock
-pubspec.lock
-
-# Directory created by dartdoc
-# If you don't generate documentation locally you can remove this line.
-doc/api/
-
-# Avoid committing generated Javascript files:
-*.dart.js
-*.info.json      # Produced by the --dump-info flag.
-*.js             # When generated by dart2js. Don't specify *.js if your
-                 # project includes source files written in JavaScript.
-*.js_
-*.js.deps
-*.js.map