[JSX] Add scope to native tags.

[Thom1729]

Requested by DouglasVarollo on Discord.

The uppercase/lowercase distinction isn't exactly syntactic, but it's not spurious either. When Babel translates JSX element to a React.createElement() call, lowercase tag names without any punctuation are translated to strings, whereas all other tags names are translated to expressions that reference variables in scope, e.g:

<foo />; // → React.createElement("foo", null);
<Foo />; // → React.createElement(Foo, null);
<foo.bar />; // → React.createElement(foo.bar, null);

This implementation will fail in cases with line breaks like <foo\n.bar />, but since this is basically cosmetic, I don't think this is a big deal.

I picked the scope entity.name.tag.native, mostly at random.