Removing an "if (this == nullptr)" check from two print methods.  The condition
will never be true in a well-defined context.  The checking for null pointers
has been moved into the caller logic so it does not rely on undefined behavior.

llvm-svn: 210498
diff --git a/clang/lib/Rewrite/Frontend/RewriteModernObjC.cpp b/clang/lib/Rewrite/Frontend/RewriteModernObjC.cpp
index 3cacbdd..43de31c 100644
--- a/clang/lib/Rewrite/Frontend/RewriteModernObjC.cpp
+++ b/clang/lib/Rewrite/Frontend/RewriteModernObjC.cpp
@@ -267,6 +267,7 @@
     }
 
     void ReplaceStmtWithRange(Stmt *Old, Stmt *New, SourceRange SrcRange) {
+      assert(Old != nullptr && New != nullptr && "Expected non-null Stmt's");
       if (DisableReplaceStmt)
         return;
 
@@ -2587,6 +2588,7 @@
 }
 
 Stmt *RewriteModernObjC::RewriteObjCStringLiteral(ObjCStringLiteral *Exp) {
+  assert (Exp != nullptr && "Expected non-null ObjCStringLiteral");
   QualType strType = getConstantStringStructType();
 
   std::string S = "__NSConstantStringImpl_";