[NFC][Clang] Fix static analyzer concern

Fix static analyzer concern about null value
dereference. InterfacePointerType is dereferenced
and should not be null.

Differential Revision: https://reviews.llvm.org/D157454

Author: elizabethandrews

clang/lib/CodeGen/CGObjC.cpp

@@ -222,6 +222,7 @@ llvm::Value *CodeGenFunction::EmitObjCCollectionLiteral(const Expr *E,
   QualType ResultType = E->getType();
   const ObjCObjectPointerType *InterfacePointerType
     = ResultType->getAsObjCInterfacePointerType();
+  assert(InterfacePointerType && "Unexpected InterfacePointerType - null");
   ObjCInterfaceDecl *Class
     = InterfacePointerType->getObjectType()->getInterface();
   CGObjCRuntime &Runtime = CGM.getObjCRuntime();