Replace further questionable HashMap::add usages in bindings

BUG=390928
R=dcarney@chromium.org

Review URL: https://codereview.chromium.org/411273002

git-svn-id: svn://svn.chromium.org/blink/trunk@178823 bbb929c8-8fbe-4397-9dbb-9b2b20218538
    bool tryGet(const v8::Handle<GCObject>& handle, T* valueOut)
    {
        typename HandleToT::iterator result = m_map.find(*handle);
        if (result != m_map.end()) {
            *valueOut = result->value;
            return true;
        }
        return false;
    }

    bool tryGet(const v8::Handle<GCObject>& handle, T* valueOut)
    {
        typename HandleToT::iterator result = m_map.find(*handle);
        if (result != m_map.end()) {
            *valueOut = result->value;
            return true;
        }
        return false;
    }
