change all patheffect methods to const, in preparation for marking its
subclasses as immutable/re-entrant safe.
Review URL: https://codereview.appspot.com/6949071

git-svn-id: http://skia.googlecode.com/svn/trunk@6877 2bbb7eff-a529-9590-31e7-b0007b416f81
14 files changed