grind doc for windows
extract _zip method
 specify the version of polymer that we use
Merge pull request #447 from dart-lang/pubspec_polymer

 specify the version of polymer that we use
Merge pull request #444 from sunglim/doc_windows

Make grind doc work on Windows.
fix a selection issue w/ non-expanded resources; fix selecting a newly created file
nit
review comments
Merge pull request #449 from dart-lang/files_selection

Files selection
when a tab is activated, focus the editing area
Merge pull request #451 from dart-lang/editor_focus

when a tab is activated, focus the editing area
Fixed #454: Don't switch tab while replacing a given tab
Merge pull request #455 from dinhviethoa/454-fix-shift-selection

Fixed #454: Don't switch tab while replacing a given tab