am 83814319: AI 149189: Adding dalvik porting guide based on content from the Android source tree under dalvik/docs/porting.html

Merge commit '838143199e2270e3f103050c76cf24539ad8dfe1' into donut

* commit '838143199e2270e3f103050c76cf24539ad8dfe1':
  AI 149189: Adding dalvik porting guide based on content from the Android source tree under dalvik/docs/porting.html