Restrict access to Version.plist in the WebContent process on iOS

https://bugs.webkit.org/show_bug.cgi?id=262699
rdar://116545792

Reviewed by Per Arne Vollan.

Access to this file provides information about the device that should not be
accessible to web content. This patch explicitly prevents access to the file
from the Web content process. In a follow up patch I'm planning on improving
the path validation we use paths provided by javascript.

* Source/WebKit/Resources/SandboxProfiles/ios/com.apple.WebKit.WebContent.sb.in:

Canonical link: https://commits.webkit.org/267815.640@safari-7617-branch

Source/WebKit/Resources/SandboxProfiles/ios/com.apple.WebKit.WebContent.sb.in

@@ -37,6 +37,9 @@
 (allow process-info-codesignature)
 #endif
 
+(deny file-read-metadata
+    (literal "/private/var/db/MobileIdentityData/Version.plist"))
+
 ;;;
 ;;; The following rules were originally contained in 'common.sb'. We are duplicating them here so we can
 ;;; remove unneeded sandbox extensions.