Fix for these bugs:

	Radar 3128622 (files that can't be mmap'd are opened twice)
	Radar 3128624 (names of "not mappable" files kept in ever-growing set)

	It turns out that simply reading in the bytes using the NSData
	initWithContentsOfFile: method is faster than attempting to mmap
	disk cache files to read them.

	Since the mmap code is now removed, the issues raised by the bugs
	simply go away.

        * Database.subproj/WebFileDatabase.m:
        (-[WebFileDatabase objectForKey:])


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@3084 268f45cc-cd09-0410-ab3c-d52691b4dbfc