Fix comments in Dart.gitignore
Fix comments in Dart.gitignore

.gitignore uses `#` for comments, not `//`
szymanskirafal/gitignore,szymanskirafal/gitignore,szymanskirafal/gitignore,bruennijs/ise.cppworkshop,bruennijs/ise.cppworkshop,bruennijs/ise.cppworkshop,chhsieh/helloworld,chhsieh/gitTest_1