[compiler] Remove dead code from js-generic-lowering.

JSLoadContext and JSStoreContext are always reduced in js-typed-lowering.

R=mstarzinger@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/2535253002
Cr-Commit-Position: refs/heads/master@{#41380}

src/compiler/js-generic-lowering.cc

@@ -286,40 +286,12 @@ void JSGenericLowering::LowerJSOrdinaryHasInstance(Node* node) {
 }
 
 void JSGenericLowering::LowerJSLoadContext(Node* node) {
-  const ContextAccess& access = ContextAccessOf(node->op());
-  for (size_t i = 0; i < access.depth(); ++i) {
-    node->ReplaceInput(
-        0, graph()->NewNode(machine()->Load(MachineType::AnyTagged()),
-                            NodeProperties::GetValueInput(node, 0),
-                            jsgraph()->Int32Constant(
-                                Context::SlotOffset(Context::PREVIOUS_INDEX)),
-                            NodeProperties::GetEffectInput(node),
-                            graph()->start()));
-  }
-  node->ReplaceInput(1, jsgraph()->Int32Constant(Context::SlotOffset(
-                            static_cast<int>(access.index()))));
-  node->AppendInput(zone(), graph()->start());
-  NodeProperties::ChangeOp(node, machine()->Load(MachineType::AnyTagged()));
+  UNREACHABLE();  // Eliminated in typed lowering.
 }
 
 
 void JSGenericLowering::LowerJSStoreContext(Node* node) {
-  const ContextAccess& access = ContextAccessOf(node->op());
-  for (size_t i = 0; i < access.depth(); ++i) {
-    node->ReplaceInput(
-        0, graph()->NewNode(machine()->Load(MachineType::AnyTagged()),
-                            NodeProperties::GetValueInput(node, 0),
-                            jsgraph()->Int32Constant(
-                                Context::SlotOffset(Context::PREVIOUS_INDEX)),
-                            NodeProperties::GetEffectInput(node),
-                            graph()->start()));
-  }
-  node->ReplaceInput(2, NodeProperties::GetValueInput(node, 1));
-  node->ReplaceInput(1, jsgraph()->Int32Constant(Context::SlotOffset(
-                            static_cast<int>(access.index()))));
-  NodeProperties::ChangeOp(
-      node, machine()->Store(StoreRepresentation(MachineRepresentation::kTagged,
-                                                 kFullWriteBarrier)));
+  UNREACHABLE();  // Eliminated in typed lowering.
 }