Find information here - http://www.mozilla.org/rhino/
Import via gradle
compile 'com.faendir.rhino:rhino-android:1.6.0'
Then, instead of calling
Context.enter()
use
new RhinoAndroidHelper(...).enterContext()
An example project can be found here.
This uses google's dx tool which can be found here - https://android.googlesource.com/platform/dalvik