[CG] Over-release in MIME type registry code
https://bugs.webkit.org/show_bug.cgi?id=115423

Reviewed by Eric Carlson.

Sam Weinig spotted these by code inspection. I don't know how to make a test demonstrating
the problem, but this is clearly an over-release.

* platform/MIMETypeRegistry.cpp:
(WebCore::initializeSupportedImageMIMETypes): Removed incorrect adoptCF call on a string we
are getting from a CFArray.
(WebCore::initializeSupportedImageMIMETypesForEncoding): Ditto.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@149375 268f45cc-cd09-0410-ab3c-d52691b4dbfc