Remove filtering inside compose

[istarkov]

1. With filtering compose does not have the well know definition of this function as like as in your comments https://github.com/reactjs/redux/blob/master/src/compose.js#L7-L9
2. Then I accidentally pass something what is not a function into compose, the only thing I could expect is an error not silent code execution. (there is no need at all to pass anything which is not a function)
3. Typed definition of compose (even you does not use it) will be really hard to create with filtering.

So I suggest you to remove this line.

[chicoxyzzy]

As a developer I expect my code to throw an Error, not eat it. Also I strongly opposite to extra useless computations in redux. Why not to filter functions outside of compose if you really need this?
So big 👍 to this PR

[alexeyraspopov]

This breaks the @evilj0e's use case described in #2073

[alexeyraspopov]

But throwing errors explicitly is definitely a better thing.

[jimbolla]

What if it were to only filter out falsey?

[chicoxyzzy]

@jimbolla why filter something at all?
The problem described in #2073 can be solved in many ways by one-liner. But the fix from #2073 is a fix of a particular codebase problems and it leads to ommited errors and performance regressions in others people code

[chicoxyzzy]

One can filter everything he wants to outside of compose. It's so easy I can't even

[timdorr]

Good points being made. Thanks!