[RM8002|RS8010] Detector clear float BUG=https://code.google.com/p/compatibility-detector/issues/detail?id=155 TEST=None
[RM8002|RS8010] Detector clear float
BUG=https://code.google.com/p/compatibility-detector/issues/detail?id=155
TEST=None

fix getNextAffectFloatingLayoutElementByNode function get node next element sibling is null bug.
bug page: http://www.shaoxiang.cn/sx/index.jsp

Review URL: http://codereview.appspot.com/4529085
linqiangl/compatibility-detector,linqiangl/compatibility-detector,linqiangl/compatibility-detector