src: check IsConstructCall in TLSWrap constructor

Currently it is possible to call TLSWrap() without using new and the
following error message:
FATAL ERROR: v8::Object::SetAlignedPointerInInternalField() Internal
field out of bounds
 1: node::Abort()
[/Users/danielbevenius/work/nodejs/node/out/Debug/node]
 2: node::OnFatalError(char const*, char const*)
[/Users/danielbevenius/work/nodejs/node/out/Debug/node]
 3: v8::Utils::ReportApiFailure(char const*, char const*)
[/Users/danielbevenius/work/nodejs/node/out/Debug/node]
 4: v8::Utils::ApiCheck(bool, char const*, char const*)
[/Users/danielbevenius/work/nodejs/node/out/Debug/node]
 5: v8::InternalFieldOK(v8::internal::Handle<v8::internal::JSReceiver>,
int, char const*)
[/Users/danielbevenius/work/nodejs/node/out/Debug/node]
 6: v8::Object::SetAlignedPointerInInternalField(int, void*)
[/Users/danielbevenius/work/nodejs/node/out/Debug/node]
 7: node::TLSWrap::Initialize(v8::Local<v8::Object>,
v8::Local<v8::Value>,
v8::Local<v8::Context>)::$_0::operator()(v8::FunctionCallbackInfo<v8::Value>
const&) const [/Users/danielbevenius/work/nodejs/node/out/Debug/node]

This commit adds a IsConstructCall check which will produce the
following error message:
/Users/danielbevenius/work/nodejs/node/out/Debug/node[2212]:
../src/tls_wrap.cc:936:auto node::TLSWrap::Initialize(Local<v8::Object>,
Local<v8::Value>, Local<v8::Context>)::(anonymous
class)::operator()(const FunctionCallbackInfo<v8::Value> &) const:
Assertion `args.IsConstructCall()' failed.
 1: node::Abort()
[/Users/danielbevenius/work/nodejs/node/out/Debug/node]
 2: node::Assert(char const* const (*) [4])
[/Users/danielbevenius/work/nodejs/node/out/Debug/node]
 3: node::TLSWrap::Initialize(v8::Local<v8::Object>,
v8::Local<v8::Value>,
v8::Local<v8::Context>)::$_0::operator()(v8::FunctionCallbackInfo<v8::Value>
const&) const [/Users/danielbevenius/work/nodejs/node/out/Debug/node]

src/tls_wrap.cc

@@ -933,6 +933,7 @@ void TLSWrap::Initialize(Local<Object> target,
   env->SetMethod(target, "wrap", TLSWrap::Wrap);
 
   auto constructor = [](const FunctionCallbackInfo<Value>& args) {
+    CHECK(args.IsConstructCall());
     args.This()->SetAlignedPointerInInternalField(0, nullptr);
   };
   auto t = env->NewFunctionTemplate(constructor);