switch travis to only test dev SDK
switch travis to only test dev SDK

R=vsm@google.com

Review URL: https://codereview.chromium.org/1223363002.

ronlobo/dev_compiler,ronlobo/dev_compiler,ochafik/dev_compiler,ochafik/dev_compiler,ronlobo/dev_compiler,ochafik/dev_compiler,ochafik/dev_compiler,ronlobo/dev_compiler