If the platform does not implements WebContext::applicationCacheDirectory (returns with null string) then the WebProcess asserts in ApplicationCacheStorage::setCacheDirectory. Since this is an optional feature we should check the value before sending it to the WebProcess.
Created attachment 67044 [details] proposed patch
Created attachment 67047 [details] proposed patch Check emptiness instead of null value since it makes more sense (and includes the null case).
Created attachment 67196 [details] proposed patch I am thoughtless. One more typo fix was needed.
Comment on attachment 67196 [details] proposed patch r=me
Comment on attachment 67196 [details] proposed patch Clearing flags on attachment: 67196 Committed r67278: <http://trac.webkit.org/changeset/67278>
All reviewed patches have been landed. Closing bug.