Refactor GetCodeCopyFromTemplate to get a single point where objects are replaced in code.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 7a1ae26bd6e874307accd856d1f905ed32204ab6..e7a374c9db8c059a332327b512beb281c842e33f 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -5372,7 +5372,6 @@ class Code: public HeapObject {
 
   // Find an object in a stub with a specified map
   Object* FindNthObject(int n, Map* match_map);
-  void ReplaceNthObject(int n, Map* match_map, Object* replace_with);
 
   // Find the first allocation site in an IC stub.
   AllocationSite* FindFirstAllocationSite();
@@ -5381,7 +5380,6 @@ class Code: public HeapObject {
   Map* FindFirstMap();
   void FindAllMaps(MapHandleList* maps);
   void FindAllTypes(TypeHandleList* types);
-  void ReplaceFirstMap(Map* replace);
 
   // Find the first handler in an IC stub.
   Code* FindFirstHandler();
@@ -5393,7 +5391,12 @@ class Code: public HeapObject {
   // Find the first name in an IC stub.
   Name* FindFirstName();
 
-  void ReplaceNthCell(int n, Cell* replace_with);
+  class FindAndReplacePattern;
+  // For each (map-to-find, object-to-replace) pair in the pattern, this
+  // function replaces the corresponding placeholder in the code with the
+  // object-to-replace. The function assumes that pairs in the pattern come in
+  // the same order as the placeholders in the code.
+  void FindAndReplace(const FindAndReplacePattern& pattern);
 
   // The entire code object including its header is copied verbatim to the
   // snapshot so that it can be written in one, fast, memcpy during