Fix Travis to run tests properly

[sophiebits]

My pull request #573 fixes the tests on master, but Travis didn't think that the tests were broken on the old one:

https://travis-ci.org/facebook/react/builds/14230968

Crucially, this looks to be because of:

TypeError: Object #<Object> has no method 'traverse'
    at /home/travis/build/facebook/react/vendor/fbtransform/transforms/react.js:150:15
    at Array.forEach (native)
    at Array.visitReactTag [as 0] (/home/travis/build/facebook/react/vendor/fbtransform/transforms/react.js:137:21)
    at walker (/home/travis/build/facebook/react/node_modules/jstransform/src/jstransform.js:202:25)
    at analyzeAndTraverse (/home/travis/build/facebook/react/node_modules/jstransform/src/utils.js:416:9)
    at traverse (/home/travis/build/facebook/react/node_modules/jstransform/src/jstransform.js:146:3)
    at traverser (/home/travis/build/facebook/react/node_modules/jstransform/src/jstransform.js:142:5)
    at analyzeAndTraverse (/home/travis/build/facebook/react/node_modules/jstransform/src/utils.js:430:9)
    at traverse (/home/travis/build/facebook/react/node_modules/jstransform/src/jstransform.js:146:3)
    at traverser (/home/travis/build/facebook/react/node_modules/jstransform/src/jstransform.js:142:5)

which I think is due to an old version of jstransform (maybe). I hit the same error on my machine and a rm -rf node_modules/jstransform; npm install fixed it. Presumably the Travis workspace was already clean though since it starts with a git clone…

Once we get Travis back on its feet it would be nice to figure out how to make it report failures like this properly instead of counting it as a pass.

[zpao]

Travis installs fresh every run, so that's pretty strange.

[zpao]

Ah, that was a legit bug in the transform :)

b250706 fixes it (we should make that fail, but let's address that separately)