Hi, thank you for creating such a great framework!
I have a feature request which I think I can contribute, but let me check if you are interested in supporting it.

### Preflight Checklist
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* [x] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
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* [x] I have searched the issue tracker for a feature request that matches the one I want to file, without success.

### Problem Description
The builtin spellchecker has been supported in https://github.com/electron/electron/pull/20692.
But it does not allow us to check spells programmatically, like [node-spellchecker](https://github.com/felixrieseberg/node-spellchecker)'s `isMisspelled` method.
Chrome's spellcheck_platform provides [CheckSpelling](https://chromium.googlesource.com/chromium/src/+/46ee392970e491fb9ee2523348e23222b40d5119/components/spellcheck/browser/spellcheck_platform.h#60) to do that exactly.

### Proposed Solution
Add a method to call `spellcheck_platform::CheckSpelling` like so:

```cc
#if BUILDFLAG(USE_BROWSER_SPELLCHECKER)
bool Session::CheckSpelling(const std::string& word) {
  if (spellcheck::UseBrowserSpellChecker()) {
    return spellcheck_platform::CheckSpelling(base::UTF8ToUTF16(word), 0);
  }
  return true;
}
#endif
```

in `shell/browser/api/atom_api_session.cc`.

It's simple and won't affect other features.

### Alternatives Considered
I don't know.

### Additional Information
None

Thanks!
shell/renderer/electron_renderer_client.cc
v8::Handle<v8::Context> context,
    content::RenderFrame* render_frame) {
  if (injected_frames_.erase(render_frame) == 0)
    return;
  node::Environment* env = node::Environment::GetCurrent(context);
  if (environments_.erase(env) == 0)
    return;
  gin_helper::EmitEvent(env->isolate(), env->process_object(), "exit");
  
  if (env == node_bindings_->uv_env())
    node_bindings_->set_uv_env(nullptr);
  
  
  
  
  
  auto* command_line = base::CommandLine::ForCurrentProcess();
  if (command_line->HasSwitch(switches::kNodeIntegrationInSubFrames) ||
      command_line->HasSwitch(
          switches::kDisableElectronSiteInstanceOverrides)) {
    node::FreeEnvironment(env);
    if (env == node_bindings_->uv_env())
      node::FreeIsolateData(node_bindings_->isolate_data());
  }
  
  electron_bindings_->EnvironmentDestroyed(env);
}
bool ElectronRendererClient::ShouldFork(blink::WebLocalFrame* frame,