Remove DOM_NODE_TYPES from Python IDL compiler

DOM_NODE_TYPES is a hard-coded list of interfaces that inherit Node.
We should instead check inheritance directly.
We can do this in Python thanks to interfaces_info;
this CL does so, considerably simplifying V8-specific type handling.

R=haraken

Review URL: https://codereview.chromium.org/133143002

git-svn-id: svn://svn.chromium.org/blink/trunk@164856 bbb929c8-8fbe-4397-9dbb-9b2b20218538