[runtime] cleanup: use the factory() for handlified values

src/runtime/runtime-debug.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/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/debug/debug-evaluate.h"
 #include "src/debug/debug-frames.h"
 #include "src/debug/debug-scopes.h"
@@ skipping 1564 matching lines @@
   } else {
     return Smi::cast(line_ends_array->get(line));
   }
 }
 
 static Handle<Object> GetJSPositionInfo(Handle<Script> script, int position,
                                         Script::OffsetFlag offset_flag,
                                         Isolate* isolate) {
   Script::PositionInfo info;
   if (!script->GetPositionInfo(position, &info, offset_flag)) {
-    return handle(isolate->heap()->null_value(), isolate);
+    return isolate->factory()->null_value();
   }
 
   Handle<String> source = handle(String::cast(script->source()), isolate);
   Handle<String> sourceText = script->type() == Script::TYPE_WASM
                                   ? isolate->factory()->empty_string()
                                   : isolate->factory()->NewSubString(
                                         source, info.line_start, info.line_end);
 
   Handle<JSObject> jsinfo =
       isolate->factory()->NewJSObject(isolate->object_function());
@@ skipping 219 matching lines @@
   Handle<Script> script = Handle<Script>(Script::cast(script_val->value()));
 
   Handle<wasm::WasmDebugInfo> debug_info =
       wasm::GetDebugInfo(handle(script->wasm_object(), isolate));
   return *wasm::WasmDebugInfo::DisassembleFunction(
       debug_info, script->wasm_function_index());
 }
 
 }  // namespace internal
 }  // namespace v8