updated various alt examples
fixed code/tweaked  previous commit
[Bug 21709] Fixing "Duplicate entries in obsolete permitted DOCTYPE table"

Editorial updates to improve readability.
https://www.w3.org/Bugs/Public/show_bug.cgi?id=21709
[giow] (3) Spec navigator.appCodeName (and respec navigator.product) constant(s)
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=22558
Affected topics: DOM APIs

git-svn-id: http://svn.whatwg.org/webapps@8038 340c8d12-0b0e-0410-8428-c7bf67bfef74
(cherry picked from commit 130d0fee9a3e597f583f784ba1edb54d1bcbbe71)
[Bug 21722] Fix boolean logic on when to show placeholder text

Fixes Bug: https://www.w3.org/Bugs/Public/show_bug.cgi?id=21722

This aligns one section of the spec with the same [corrected] logic in
another part of the spec: the placeholder text should NOT show when just
the element is not focused...
alt example tweaks +start of logo section
additions to logo section
WebVTT spec moved from WebVTTCue to VTTCue:
http://dev.w3.org/html5/webvtt/#dfn-vttcue
Fixed IDL for createPattern

Most browsers allow null or the empty string for the second argument to createPattern.
Fixed IDL and prose to reflect this
updated measuretext() lists

Added a 4th clause that explains about the security aspect of the fonts,
and added back in the width item on the list. Changed some of the text
to reflect the use of another element in the spec (text preparation
algorithm).
modded log examples
added another logo example
incorrect image height/width
swapped webplatform images
typo
tweaked html5 logo example
style tweak
fixed unclosed div
typo
Cleaned up imageSmoothingEnabled text

Fixed some broken sentences, and made the prose a little clearer.