ASSERT(!m_referencedNodes.size()) in AudioContext's destructor should be enabled in oilpan builds

Given that we clear the m_referencedNodes in AudioContext::uninitialize(),
the m_referencedNodes should be empty in both oilpan builds and non-oilpan builds.

BUG=340522

Review URL: https://codereview.chromium.org/475373002

git-svn-id: svn://svn.chromium.org/blink/trunk@180423 bbb929c8-8fbe-4397-9dbb-9b2b20218538