Updated implementation of elementReplace.

This implementation works for void elements and is actually simpler than
the old one.
code review comments
minor event handler namespace cleanup
Merge pull request #4975 from adobe/jasonsanjose/issue-4966-rebase

Fix live dev issues after ResearchLiveHTML merge
fix #4623: remove unused _isEmptyTag function
When applying text or attribute value edits, decode entities
Merge branch 'master' of https://github.com/adobe/brackets into larz/twipsy
Stripped out unncessary overrides based on randy's feedback.
Fixed conflict.
Fixed conflicts.
Cleaned up spaces.
Do not apply HTMLDocument edits if instrumentation is not enabled
code review comments
typo
Fixed indent spacing.
Tweaked colors.
No need to use .opacity() anymore since opacity is supported on all major browsers.
Fix two bugs with spurious dirtyFlagChange events:
- Document ctor always fires it, even though isDirty stays false whole time
- Calling refreshText() always fires a pair of isDirty->true,->false
  (causing bug #502)

Add unit tests for various cases around Document dirty/undo state
Update tern/acorn to the latest
Fix unit tests by adding innerHTML/textContent support.