[contexts] Place the initial JSArray maps on the native context directly.

src/crankshaft/hydrogen.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/crankshaft/hydrogen.h"
 
 #include <sstream>
 
 #include "src/allocation-site-scopes.h"
 #include "src/ast/ast-numbering.h"
@@ skipping 3409 matching lines @@
     return builder()->Add<HLoadNamedField>(constructor_function_, nullptr,
                                            access);
   }
 
   // TODO(mvstanton): we should always have a constructor function if we
   // are creating a stub.
   HInstruction* native_context = constructor_function_ != NULL
       ? builder()->BuildGetNativeContext(constructor_function_)
       : builder()->BuildGetNativeContext();
 
-  HInstruction* index = builder()->Add<HConstant>(
-      static_cast<int32_t>(Context::JS_ARRAY_MAPS_INDEX));
-
-  HInstruction* map_array = builder()->Add<HLoadKeyed>(
-      native_context, index, nullptr, nullptr, FAST_ELEMENTS);
-
-  HInstruction* kind_index = builder()->Add<HConstant>(kind_);
-
-  return builder()->Add<HLoadKeyed>(map_array, kind_index, nullptr, nullptr,
-                                    FAST_ELEMENTS);
+  HObjectAccess access =
+      HObjectAccess::ForContextSlot(Context::ArrayMapIndex(kind_));
+  return builder()->Add<HLoadNamedField>(native_context, nullptr, access);
 }
 
 
 HValue* HGraphBuilder::JSArrayBuilder::EmitInternalMapCode() {
   // Find the map near the constructor function
   HObjectAccess access = HObjectAccess::ForPrototypeOrInitialMap();
   return builder()->Add<HLoadNamedField>(constructor_function_, nullptr,
                                          access);
 }
 
@@ skipping 10172 matching lines @@
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 }  // namespace internal
 }  // namespace v8