Revert 157959 "Introduce a new reference graph to SVG*TearOffs."
Revert 158014 "Hold onto contextElement() from SVGAnimated* wrap..."

TBR=pdr@chromium.org,haraken@chromium.org
BUG=270000
BUG=294464

Review URL: https://chromiumcodereview.appspot.com/24863002

git-svn-id: svn://svn.chromium.org/blink/trunk@158408 bbb929c8-8fbe-4397-9dbb-9b2b20218538