[SVG] SVGAnimatedInteger{,OptionalInteger} migration to new SVG property impl.

This CL replaces SVGAnimatedInteger{,OptionalInteger} with NewSVGProperty based implementation.

For details, see design doc: https://docs.google.com/document/d/1bg7CUyUszqdwmENY3JX6_PoQD6uHRCNcRPJMlC4qlkw/edit?usp=sharing

BUG=308818

Review URL: https://codereview.chromium.org/153603002

git-svn-id: svn://svn.chromium.org/blink/trunk@167167 bbb929c8-8fbe-4397-9dbb-9b2b20218538