bindings: Don't throw a TypeError when 'null' is passed to nullable callback function

third_party/WebKit/Source/bindings/templates/callback_function.h.tmpl

 {% filter format_blink_cpp_source_code %}
 
 {% include 'copyright_block.txt' %}
 
 #ifndef {{cpp_class}}_h
 #define {{cpp_class}}_h
 
 {% for filename in header_includes %}
 #include "{{filename}}"
 {% endfor %}
 
 namespace blink {
 
 class ScriptState;
 {% for forward_declaration in forward_declarations %}
 class {{forward_declaration}};
 {% endfor %}
 
 class {{exported}}{{cpp_class}} final : public GarbageCollectedFinalized<{{cpp_class}}>, public TraceWrapperBase {
  public:
-  static {{cpp_class}}* create(ScriptState* scriptState, v8::Local<v8::Function> callback)  {
-    return new {{cpp_class}}(scriptState, callback);
-  }
+  static {{cpp_class}}* create(ScriptState* scriptState, v8::Local<v8::Value> callback);
 
   ~{{cpp_class}}() = default;
 
   DECLARE_TRACE();
   DECLARE_TRACE_WRAPPERS();
 
   bool call({{argument_declarations | join(', ')}});
 
   v8::Local<v8::Function> v8Value(v8::Isolate* isolate) {
     return m_callback.newLocal(isolate);
   }
 
   void setWrapperReference(v8::Isolate* isolate, const v8::Persistent<v8::Object>& wrapper) {
     DCHECK(!m_callback.isEmpty());
     m_callback.setReference(wrapper, isolate);
   }
 
  private:
   {{cpp_class}}(ScriptState*, v8::Local<v8::Function>);
 
   RefPtr<ScriptState> m_scriptState;
   TraceWrapperV8Reference<v8::Function> m_callback;
 };
 
 }  // namespace blink
 
 #endif  // {{cpp_class}}_h
 
 {% endfilter %}{# format_blink_cpp_source_code #}