A use-after-free issue was discovered in libwebm through 2018-02-02. If a Vp9HeaderParser was initialized once before, its property frame_ would not be changed because of code in vp9parser::Vp9HeaderParser::SetFrame. Its frame_ could be freed while the corresponding pointer would not be updated, leading to a dangling pointer. This is related to the function OutputCluster in webm_info.cc.
