workspace changes for d&d
Merge branch 'master' into work
modify resource change event
upgraded chrome package
fire change event at end of move
add comment
merge master
Merge pull request #309 from dart-lang/dnd

Drag and drop between folders in tree view
Introduce a single base class for Spark widgets
A hacky image viewer
Introduce animation when showing/hiding tabs
Minor adjustments
Undo unrelated change
Nit
Merge pull request #322 from ussuri/common-base-polymer-widget

Introduce a common base class for Polymer widgets
Fixed #321: Made the menu button similar to the Chrome button. Also applied some other UI tweaks.
Formalize expected author's CSS classes + improve spark-button attributes handling
Formalize author's CSS use + improve spark-button attribute handling
Merge pull request #326 from ussuri/formalize-author-css-use

Formalize external author's CSS use in Polymer widgets
Add a Widget method to more easily construct CSS class strings