[cleanup] Refactor maybe-handle to use default members.

Fixing clang-tidy warning.

Bug: v8:8015
Change-Id: I8546c58afbac278a764067173570b433dff6674d
Reviewed-on: https://chromium-review.googlesource.com/1224413Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Florian Sattler <sattlerf@google.com>
Cr-Commit-Position: refs/heads/master@{#55896}

src/maybe-handles.h

@@ -23,7 +23,7 @@ namespace internal {
 template <typename T>
 class MaybeHandle final {
  public:
-  V8_INLINE MaybeHandle() {}
+  V8_INLINE MaybeHandle() = default;
 
   // Constructor for handling automatic up casting from Handle.
   // Ex. Handle<JSArray> can be passed when MaybeHandle<Object> is expected.

src/wasm/module-compiler.cc

@@ -1039,7 +1039,6 @@ MaybeHandle<WasmInstanceObject> InstanceBuilder::Build() {
   //--------------------------------------------------------------------------
   // Set up the globals for the new instance.
   //--------------------------------------------------------------------------
-  MaybeHandle<JSArrayBuffer> old_globals;
   uint32_t globals_buffer_size = module_->globals_buffer_size;
   if (globals_buffer_size > 0) {
     void* backing_store =