Remove css transform hack
Merge pull request #205 from domchristie/fix-missing-scollbars

Fix Missing Scrollbars
Add split-view styles and markup inspired by Chrome dev tools
Sharpen View Tree and Promises nav icons
Flatten gradients in line with chrome dev-tools styles
Add sidebar-toggle component
Remove app__toggle-inspector-btn styles (replaced by sidebar-toggle component)
Improve drag-handle component
Convert sidebar toggle component to button element
Remove nav link focus styles
Add resizable-column component
Use two split-views for app layout. Move iframes dropdown to sidebar header
Fix nav column width
Add TabRoute to render resource toolbars
Remove filter bar from render tree template (in favour of a toolbar)
Fix list view height calculation (filter bar height consideration not needed with flex-box)
Improve sidebar toggle icon cros-browser rendering
Add clear-button component
Ensure main split view header is rendered into the application template
Add toolbar-item styles. Improve toolbar item markup