[Objective-C Sema] Fixes a typo which did not allow 
bridge casting to super class of object's bridge type.
rdar://18311183


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@234652 91177308-0d34-0410-b5e6-96231b3b80d8

• lib/Sema/SemaExprObjC.cpp[diff]
• test/SemaObjC/objcbridge-attribute-arc.m[diff]
• test/SemaObjC/objcbridge-attribute.m[diff]
• test/SemaObjC/objcbridgemutable-attribute.m[diff]
• test/SemaObjCXX/objcbridge-attribute-arc.mm[diff]
• test/SemaObjCXX/objcbridge-attribute.mm[diff]
• test/SemaObjCXX/objcbridge-static-cast.mm[diff]