fix handler argument annotations

[Hanaasagi]

This pull request wants to make handler annotation correct.

When using Mypy to check following code,

from aiohttp import web


class MyView(web.View):
    async def get(self):
        return web.Response(text="Hello world")


app = web.Application()
app.add_routes([web.view('/', MyView)])  # line 10
web.run_app(app)

It will report

t.py:10: error: Argument 2 to "view" has incompatible type "Type[MyView]"; expected "AbstractView"                                                                                           

web.view accepts subclass of AbstractView type variable as handler, instead of an instance.

resolve #3653

[Hanaasagi]

It seems like a small change, I will add changelog if you really need.

[kornicameister]

@Hanaasagi check out #3633 . Seems you've duplicated my work ;-)

[Hanaasagi]

Oh, I'm Sorry for this.

[kornicameister]

@Hanaasagi no biggie ;-).