Provide mutators in NodeProperties instead of exposing indicies.

src/compiler/node-properties.h

Index: src/compiler/node-properties.h
diff --git a/src/compiler/node-properties.h b/src/compiler/node-properties.h
index eaa4d66ada1c593aab3c8530b2e4292c60879077..40fcbfdb0d79becc17a9425d18b218b48b86806c 100644
--- a/src/compiler/node-properties.h
+++ b/src/compiler/node-properties.h
@@ -31,6 +31,7 @@ class NodeProperties {
 
   static inline bool IsControl(Node* node);
 
+  static inline void ReplaceControlInput(Node* node, Node* control);
   static inline void ReplaceEffectInput(Node* node, Node* effect,
                                         int index = 0);
   static inline void RemoveNonValueInputs(Node* node);
@@ -38,9 +39,9 @@ class NodeProperties {
   static inline Bounds GetBounds(Node* node);
   static inline void SetBounds(Node* node, Bounds bounds);
 
-  static inline int GetContextIndex(Node* node);
-
+ private:
   static inline int FirstValueIndex(Node* node);
+  static inline int FirstContextIndex(Node* node);
   static inline int FirstEffectIndex(Node* node);
   static inline int FirstControlIndex(Node* node);
   static inline int PastValueIndex(Node* node);