Fix Proto module's path
Fix Proto module's path

The output was moved to out/proto/java. This then basically caused any exported
java classes referring to these classes to be silently dropped from the output
javascript :/

TEST=`ant package && grep applyWith out/package/domdistiller.js`

TBR=yfriedman

Review URL: https://codereview.chromium.org/271803003

dalmirdasilva/dom-distiller,dalmirdasilva/dom-distiller,dalmirdasilva/dom-distiller,dalmirdasilva/dom-distiller,dalmirdasilva/dom-distiller