[std] haxe.io.Input.readAll method always throws Error.Blocked

When implementing only `haxe.io.Input.readByte` method, leaving out base `haxe.io.Input.readAll` implementation, an `Error.Blocked` is always thrown.

To reproduce run following code:
```
class Test {
static function main() {
trace(new haxe.io.StringInput("test input").readAll().toString() == "test input");
}
}
```
after commenting out `haxe.io.BytesInput.readBytes` method first.

Solution would be to remove a loop (and a try-catch since it's not really needed) in a `haxe.io.Input.readAll` method.