Disable flaky WebViewInteractiveTest.DragDropWithinWebView

BUG=309032
TBR=lazyboy@chromium.org

Review URL: https://codereview.chromium.org/29153003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229562 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229562