plugins/npruntime/evaluate-js-destroying-plugin-from-destroy-stream.html was added in http://trac.webkit.org/changeset/78157 It has been failing on SnowLeaoprd Release (Tests) since being added.
<rdar://problem/8982077>
The same revision seems to be some of WebKit2 plugin tests to crash or fail: Tests where results did not match expected results: plugins/npruntime/evaluate.html expected actual diff pretty diff Tests that caused the Web process to crash: plugins/npruntime/get-int-identifier-special-values.html
I'm going to use this bug to track adding the test back.
Mass closing plug-in bugs, as plug-in support has been removed from WebKit. Please comment and/or reopen if this still affects WebKit in some way.