Fix null dereference in AudioNode::processIfNecessary
Fix null dereference in AudioNode::processIfNecessary

This is a speculative fix. As far as I see the crash report, it seems that numberOfInputs() becomes 0 in AudioDestinationNode::render (though I don't know how it happens). This CL adds a branch to handle the situation.

BUG=437636

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=189951

Review URL: https://codereview.chromium.org/907773003

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@190019 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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