Issue 6177: Replace mutation events with mutation observers for the HTML panel

http://code.google.com/p/fbug/issues/detail?id=6177
Clean up lib/wrapper a bit
Add Wrapper.wrapObject
Add Wrapper.isDeadWrapper
Wrap elements passed to Inspector.highlightObject
Use mutation observers for finding <link> changes in the CSS panel
Add a try-catch around mutateNode

Dunno if this is needed, but it was in callers before.
Revert "Properly select the element after editing (related to issue 5506)"

The fix no longer works now that mutations are more async.

This reverts commit 91a84e627be18381714537237c01fda8b4db9e7a.
Fix a test

Through changes to event order, .normalize() now highlights the whole
element instead of just its text content. (That's acceptable though.)
Set selection highlighting if the selected node is just created
Clean up observers in the CSS panel
Naming, comment nits
Make the breakOnElement test correctly test removal breakpoints
Throttle individual mutations
Merge pull request #71 from simonlindholm/mutationobservers

Mutation observers for HTML, CSS panel + misc fixes