[SVG] Remove SVGAttributeToPropertyMap

This was used to resolve property types for the old svg property implementation, but it is not used anymore.

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

Review URL: https://codereview.chromium.org/189263005

git-svn-id: svn://svn.chromium.org/blink/trunk@168706 bbb929c8-8fbe-4397-9dbb-9b2b20218538