Based on the original patch from danemacmillan.
* suggestion-picker.js
Add a new shared util to find the most popular css property in an array.
The list of popular css properties is extracted from chrome devtools code.
* autocomplete-popup.js
Can specify selected item index when opening the popup or setting items.
* inplace-editor.js
Use the suggestion-picker to select a default property.
MozReview-Commit-ID: JuWZzbBSBqX
--HG--
extra : rebase_source : 3317766ae63aea83f845d3cf3d134ecf60135f67
