Produce toClassName(const RefPtr<T>&) by DEIFNE_NODE_TYPE_CASTS.

We can remove '.get()' in toClassName(refPtr.get()) with this conversion
function.
We produce a function with "const RefPtr<any type>&" argument, not "const
RefPtr<Node>&" because "const RefPtr<Node>&" doesn't accept
RefPtr<ContainerNode>, etc.

BUG=309516
TEST=none; no behavior changes.

Review URL: https://codereview.chromium.org/31713004

git-svn-id: svn://svn.chromium.org/blink/trunk@160179 bbb929c8-8fbe-4397-9dbb-9b2b20218538