Create method doesn't consider the expected `return` type

[FMorschel]

Repro:

void f() {
  var list = <A>[];
  list.where((a) {
    return a.newMethod();
  });
}

class A {}

This should produce bool newMethod() {} but it produces void newMethod() {}.

[FMorschel]

Here is the CL https://dart-review.googlesource.com/c/sdk/+/417780