Fixed <rdar://problem/4042570> Need to check image properties for presence of width...

	Fixed <rdar://problem/4042570> Need to check image properties for presence of width/height properties

	ImageIO-55 changed how image properties are created.  They
	are now created incrementally.  So we need "re-get" the image
	properties if the properties we care about (width/height) aren't
	in the property dictionary.

        Reviewed by John.

        * WebCoreSupport.subproj/WebImageData.h:
        * WebCoreSupport.subproj/WebImageData.m:
        (-[WebImageData init]):
        (-[WebImageData fileProperties]):
        (-[WebImageData propertiesAtIndex:]):
        (-[WebImageData _isSizeAvailable]):
        (-[WebImageData incrementalLoadWithBytes:length:complete:callback:]):
        (-[WebImageData size]):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@8828 268f45cc-cd09-0410-ab3c-d52691b4dbfc