[turbofan] Make global variable loads and stores explicit.

test/unittests/compiler/js-typed-lowering-unittest.cc

 // Copyright 2014 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/code-factory.h"
 #include "src/compiler/access-builder.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/js-operator.h"
 #include "src/compiler/js-typed-lowering.h"
 #include "src/compiler/machine-operator.h"
@@ skipping 867 matching lines @@
       Handle<String>(isolate()->heap()->nan_string(), isolate())  // --
   };
   Matcher<Node*> matches[] = {
       IsHeapConstant(Unique<HeapObject>::CreateImmovable(
           Handle<HeapObject>(isolate()->heap()->undefined_value(), isolate()))),
       IsNumberConstant(std::numeric_limits<double>::infinity()),
       IsNumberConstant(IsNaN())  // --
   };
 
   VectorSlotPair feedback;
-  Node* global = Parameter(Type::GlobalObject());
+  Node* global = UndefinedConstant();
   Node* vector = UndefinedConstant();
   Node* context = UndefinedConstant();
   Node* effect = graph()->start();
   Node* control = graph()->start();
 
   for (size_t i = 0; i < arraysize(names); i++) {
     Unique<Name> name = Unique<Name>::CreateImmovable(names[i]);
     Reduction r = Reduce(graph()->NewNode(
-        javascript()->LoadNamed(name, feedback), global, vector, context,
+        javascript()->LoadGlobal(name, feedback), global, vector, context,
         EmptyFrameState(), EmptyFrameState(), effect, control));
 
     ASSERT_TRUE(r.Changed());
     EXPECT_THAT(r.replacement(), matches[i]);
   }
 }
 
 
 // -----------------------------------------------------------------------------
 // JSLoadDynamicGlobal
@@ skipping 185 matching lines @@
   EXPECT_THAT(r.replacement(),
               IsFinish(IsAllocate(IsNumberConstant(Context::SizeFor(
                                       Context::MIN_CONTEXT_SLOTS)),
                                   effect, control),
                        _));
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8