title: Incorrect path file reference to packages when sharing solution between mac and windows
body: <p>I have solution/flutter app running on <strong>windows</strong> fine.  Within the .packages file vscode is referencing the package via </p>
  
  <pre><code>analyzer:file:///c:/flutter/.pub-cache/hosted/pub.dartlang.org/analyzer-0.31.2-alpha.2/lib/
  args:file:///c:/flutter/.pub-cache/hosted/pub.dartlang.org/args-1.4.3/lib/
  async:file:///c:/flutter/.pub-cache/hosted/pub.dartlang.org/async-2.0.7/lib/
  ...
  </code></pre>
  
  <p>I have the flutter sdk installed c:\flutter directory on windows.</p>
  
  <p>I copied this solution via dropbox to the <strong>mac</strong> and when running </p>
  
  <p>"Warning! This package referenced a Flutter repository via the .packages file that is no longer available".  </p>
  
  <p>In an effort to isolate/locate the problem, I created a new Flutter project on the mac and found that the .packages file referenced packages via </p>
  
  <pre><code>analyzer:file:///flutter/.pub-cache/hosted/pub.dartlang.org/analyzer-0.31.2-alpha.2/lib/
  args:file:///flutter/.pub-cache/hosted/pub.dartlang.org/args-1.4.3/lib/
  async:file:///flutter/.pub-cache/hosted/pub.dartlang.org/async-2.0.7/lib/
  ...
  </code></pre>
  
  <p><strong>Notice</strong> the different paths used on both systems.</p>
  
  <p>I suspect I can search/replace the references file:///c:/flutter to file:///flutter and it should work but I would like to avoid always manually swapping out locations.  Is there an easier approach when sharing solutions across mac and windows? </p>
  
  <p>thx</p>