WebKit should not decode or support PDF favicons
https://bugs.webkit.org/show_bug.cgi?id=114650
<rdar://problem/10133914>

Reviewed by Dan Bernstein.

Drop the image data on the floor if it begins with the PDF magic number.
No other browser I can find on OS X supports PDF favicons (by experimentation),
and we do not properly display them.

* loader/icon/IconLoader.cpp:
(WebCore::IconLoader::notifyFinished):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@148758 268f45cc-cd09-0410-ab3c-d52691b4dbfc