Fix ambiguous reference to overloaded definition

[exoego]

Fixed the below compile error.

[error] /home/vagrant/IdeaProjects/scala-js-dom/src/main/scala/org/scalajs/dom/ext/Extensions.scala:279:33: ambiguous reference to overloaded definition,
[error] both method position in class ByteBuffer of type (x$1: Int)java.nio.ByteBuffer
[error] and  method position in class Buffer of type ()Int
[error] match expected type ?
[error]         val origPosition = data.position
[error]                                 ^