swift234

[ObjC Interop] Map Swift @objc properties named isFoo to ObjC Cocoa conventions

The Objective-C Cocoa convention eschew "is" on property names, but
use it on the getter, while the Swift API guidelines state that
Boolean properties should read as assertions (e.g., "isEmpty" rather
than "empty"). Map Swift properties named "isFoo" to Objective-C by
removing the "is" from the resulting Objective-C property name (so it
will be named "foo") and from the setter (which will have the
Objective-C selector "setFoo:") while retaining the "is" for the
getter selector ("isFoo").

Fixes rdar://problem/17090661.