IDL compiler: Remove special case of SVGAnimated* wrapper code

This removes the special case for SVGAnimated* wrapper code,
by replacing it with [SetWrapperReferenceTo(SVGElement contextElement)]
and removing the code from the Perl CG;
no changes to generated bindings.
(Fixes 17/24 V8SVGAnimated* files.)

Followup to:
IDL compiler: Regularize SVGAnimated* wrapper code
https://codereview.chromium.org/176953002/

BUG=239771
TBR=haraken, kouhei

Review URL: https://codereview.chromium.org/176923003

git-svn-id: svn://svn.chromium.org/blink/trunk@167756 bbb929c8-8fbe-4397-9dbb-9b2b20218538