text/template: remove duplicate logic in conditional

It looks like this conditional may have been refactored at some point,
but the logic was still very confusing. The outer conditional checks if
the function is variadic, so there's no need to verify that in the
result. Additionally, since the function isn't variadic, there is no
reason to permit the function call if the number of input arguments is
less than the function signature requires.

Change-Id: Ia957cf83d1c900c08dd66384efcb74f0c368422e
Reviewed-on: https://go-review.googlesource.com/35491
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/text/template/exec.go

@@ -628,7 +628,7 @@ func (s *state) evalCall(dot, fun reflect.Value, node parse.Node, name string, a
 		if numIn < numFixed {
 			s.errorf("wrong number of args for %s: want at least %d got %d", name, typ.NumIn()-1, len(args))
 		}
-	} else if numIn < typ.NumIn()-1 || !typ.IsVariadic() && numIn != typ.NumIn() {
+	} else if numIn != typ.NumIn() {
 		s.errorf("wrong number of args for %s: want %d got %d", name, typ.NumIn(), len(args))
 	}
 	if !goodFunc(typ) {