CodeGen: Avoid ilist iterator implicit conversions in a few more places, NFC

llvm-svn: 249880
diff --git a/llvm/lib/CodeGen/MachineBlockFrequencyInfo.cpp b/llvm/lib/CodeGen/MachineBlockFrequencyInfo.cpp
index 10b0e92..9119e31 100644
--- a/llvm/lib/CodeGen/MachineBlockFrequencyInfo.cpp
+++ b/llvm/lib/CodeGen/MachineBlockFrequencyInfo.cpp
@@ -57,7 +57,7 @@
 
   static inline
   const NodeType *getEntryNode(const MachineBlockFrequencyInfo *G) {
-    return G->getFunction()->begin();
+    return &G->getFunction()->front();
   }
 
   static ChildIteratorType child_begin(const NodeType *N) {