Based Dart mode on C/C++ mode so that at least the indentation basics
are acceptable (e.g. indentation after curly braces).
Fixed some higlighting rules to match modern Dart.
of keyword
Fix Dart test
Removed outdated keywords
Merge pull request #1358 from ajaxorg/dart-based-on-c

Based Dart mode on C/C++ mode so that at least the indentation basics