The politics with Swift are well understood - it's simply an alternative to Objective-C that is technically superior in. A bunch of ways. Objective-C is effectively proprietary, so if you are willing to program Objective-C, you are presumably ok with programming on Apple's platform and it's just a straightforward technical choice.
Dart is an alternative to JavaScript, and the politics are a lot more murky. JavaScript is the open language of the web and is not controlled by a single vendor. Although Google has opaquely submitted Dart to ECMA, the politics are much less clear, and of course they have given themselves a multi-year head start in implementing and understanding the language. Supporting Dart involves risking handing even more control over the web to Google.
Google submitting Dart to ECMA is no different from Microsoft submitting .NET to ECMA, alongside the .NET early versions source code (I forgot how it was called).
Agreed. It really just tags a particular version of the language. It gives zero commitment from Google about how the language will be evolved or deployed. Unless they do a lot more to make the language into a commons, it's really just a PR move so they can say 'but standards'.
Dart is an alternative to JavaScript, and the politics are a lot more murky. JavaScript is the open language of the web and is not controlled by a single vendor. Although Google has opaquely submitted Dart to ECMA, the politics are much less clear, and of course they have given themselves a multi-year head start in implementing and understanding the language. Supporting Dart involves risking handing even more control over the web to Google.