Remove prototype checks for leaf maps in optimized code.

src/x64/lithium-codegen-x64.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 38 matching lines @@
       : zone_(info->zone()),
         chunk_(static_cast<LPlatformChunk*>(chunk)),
         masm_(assembler),
         info_(info),
         current_block_(-1),
         current_instruction_(-1),
         instructions_(chunk->instructions()),
         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),
         translations_(info->zone()),
         deferred_(8, info->zone()),
         osr_pc_offset_(-1),
         last_lazy_deopt_pc_(0),
         frame_is_built_(false),
         safepoints_(info->zone()),
         resolver_(this),
@@ skipping 295 matching lines @@
   LPlatformChunk* const chunk_;
   MacroAssembler* const masm_;
   CompilationInfo* const info_;
 
   int current_block_;
   int current_instruction_;
   const ZoneList<LInstruction*>* instructions_;
   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_;
   TranslationBuffer translations_;
   ZoneList<LDeferredCode*> deferred_;
   int osr_pc_offset_;
   int last_lazy_deopt_pc_;
   bool frame_is_built_;
 
   // Builder that keeps track of safepoints in the code. The table
@@ skipping 58 matching lines @@
   LCodeGen* codegen_;
   Label entry_;
   Label exit_;
   Label* external_exit_;
   int instruction_index_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_LITHIUM_CODEGEN_X64_H_