Code styling improvements
Check breakpoint existence (related to issue 7470)
Issue 7473: 	Jump to functions doesn't work within frames
[firebug-2.0b7]
Don't default to the current global in DebuggerLib's getDebuggeeGlobal methods

It's almost always a bug (see e.g. issue 7473), and explicit is better
than implicit.
FBTest for issue 7470: Breakpoint conditions are disregarded.
fix the typo.
Issue 6557: Forgotten changes to revert
Issue 6557: fix FBTest of issue css/4683/issue4683.js
Merge remote-tracking branch 'origin/master' into issue6557
Issue 6557: make sure the URL exists for font objects