[turbofan] Remove obsolete code.

Change-Id: I9e5eb7132da7e11ab4427fc07bacee667df3ef41
Reviewed-on: https://chromium-review.googlesource.com/c/1270587Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56479}

src/compiler/js-native-context-specialization.cc

@@ -55,12 +55,6 @@ bool HasOnlyJSArrayMaps(MapHandles const& maps) {
 
 }  // namespace
 
-struct JSNativeContextSpecialization::ScriptContextTableLookupResult {
-  Handle<Context> context;
-  bool immutable;
-  int index;
-};
-
 JSNativeContextSpecialization::JSNativeContextSpecialization(
     Editor* editor, JSGraph* jsgraph, JSHeapBroker* js_heap_broker, Flags flags,
     Handle<Context> native_context, CompilationDependencies* dependencies,

src/compiler/js-native-context-specialization.h

@@ -223,11 +223,6 @@ class V8_EXPORT_PRIVATE JSNativeContextSpecialization final
   InferHasInPrototypeChainResult InferHasInPrototypeChain(
       Node* receiver, Node* effect, Handle<HeapObject> prototype);
 
-  // Script context lookup logic.
-  struct ScriptContextTableLookupResult;
-  bool LookupInScriptContextTable(Handle<Name> name,
-                                  ScriptContextTableLookupResult* result);
-
   Graph* graph() const;
   JSGraph* jsgraph() const { return jsgraph_; }