alwu, maybe you can take a look? If I click on the crash signature at the top of this bug report, I see quite a few crash reports since bug 1533909 landed (including 3 crash reports from recent Nightly which were submitted today). So it looks like there are other ways of triggering this crash, which bug 1533909's patches didn't fully address.
Bug 1537554 Comment 1 Edit History
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alwu, maybe you can take a look? If I click on the crash signature at the top of this bug report, I see quite a few crash reports since bug 1533909 landed (including 3 crash reports from recent Nightly which were submitted today, of which I am one). So it looks like there are other ways of triggering this crash, which bug 1533909's patches didn't fully address.