use styleSheetAdded and styleSheetRemoved to replace deleted getAllStylesheets API
fix related doc ref count errors
fallback to getAllStyleSheets if available
add error handling when getAllStyleSheets is not found in inspector protocol
do not change live dev status for inspector errors
account for styleSheetId changes after a CSSDocument reloads
remove styleSheetRemoved handler. handle weird chrome behavior where interim updates cause spurious added/removed events.
fix jslint error. Fix getSourceFromBrowser response. Remove debounce for CSSDocument.
fix failing unit tests. restore CSSDocument initial call to _updateBrowser.
Merge remote-tracking branch 'origin/master' into jasonsanjose/issue-6830
remove extraneous reject for _openDeferred
Ignore LiveDevelopment.close() if not active
Merge remote-tracking branch 'origin/master' into jasonsanjose/issue-6830
Merge branch 'jasonsanjose/issue-6830' of https://github.com/adobe/brackets into jasonsanjose/issue-6830
Improve working-set context menu UI/UX

This commit refers to issue #6012
It rearrange items whitin the working sets and move all those related
to "sorting" to a new drop down menu accessible through a new cog
button in the working set header
Reduce cog size to 13px
Reduce cog opacity for non-hover status
Fix cog color and position
Add tests for ContextMenu#isOpen
Refactor work set menu sorting event handler