Remove prototype checks for leaf maps in optimized code.

src/x64/lithium-codegen-x64.h

Index: src/x64/lithium-codegen-x64.h
diff --git a/src/x64/lithium-codegen-x64.h b/src/x64/lithium-codegen-x64.h
index ae1fe2c8caa937a76036d9c12d5944e14cc90ecd..f4c18d6f77e6b4fd0ece4b57784f4d5a6cd044f5 100644
--- a/src/x64/lithium-codegen-x64.h
+++ b/src/x64/lithium-codegen-x64.h
@@ -56,6 +56,7 @@ class LCodeGen BASE_EMBEDDED {
         deoptimizations_(4, info->zone()),
         jump_table_(4, info->zone()),
         deoptimization_literals_(8, info->zone()),
+        prototype_maps_(0, info->zone()),
         inlined_function_count_(0),
         scope_(info->scope()),
         status_(UNUSED),
@@ -367,6 +368,7 @@ class LCodeGen BASE_EMBEDDED {
   ZoneList<LEnvironment*> deoptimizations_;
   ZoneList<JumpTableEntry> jump_table_;
   ZoneList<Handle<Object> > deoptimization_literals_;
+  ZoneList<Handle<Map> > prototype_maps_;
   int inlined_function_count_;
   Scope* const scope_;
   Status status_;