bindings: Throw a TypeError when a given callback function isn't callable

third_party/WebKit/Source/bindings/templates/methods.cpp.tmpl

Index: third_party/WebKit/Source/bindings/templates/methods.cpp.tmpl
diff --git a/third_party/WebKit/Source/bindings/templates/methods.cpp.tmpl b/third_party/WebKit/Source/bindings/templates/methods.cpp.tmpl
index 9d3e726aaf15fdabe48c4568727bec62f5e7bad2..a4fb97619af188d899c3abdbb07e50c4dd40c0f0 100644
--- a/third_party/WebKit/Source/bindings/templates/methods.cpp.tmpl
+++ b/third_party/WebKit/Source/bindings/templates/methods.cpp.tmpl
@@ -177,7 +177,7 @@ if (info.Length() <= {{argument.index}} || !{% if argument.is_nullable %}(info[{
 {% endif %}{# argument.is_optional #}
 {% endif %}{# argument.idl_type == 'EventListener' #}
 {% elif argument.is_callback_function %}
-if (!info[{{argument.index}}]->IsFunction(){% if argument.is_nullable %} && !info[{{argument.index}}]->IsNull(){% endif %}) {
+if (!info[{{argument.index}}]->IsObject() || !v8::Local<v8::Object>::Cast(info[{{argument.index}}])->IsCallable()) {
   {{throw_argument_error(method, argument, "The callback provided as parameter %(index)d is not a function.")}}
   return;
 }