[SVG] rm SVGProperty{,TearOff}.h

These files were no longer referenced from any file. We already migrated to NewSVGProperty implementation.

NOTRY=true
TBR=haraken,fs,pdr
BUG=349370

Review URL: https://codereview.chromium.org/194083003

git-svn-id: svn://svn.chromium.org/blink/trunk@168905 bbb929c8-8fbe-4397-9dbb-9b2b20218538