Spec is being changed as described here: https://www.w3.org/Bugs/Public/show_bug.cgi?id=15647 We basically need to change our definition from: <feFuncR type="linear" slope="[amount]"/> ... to: <feFuncR type="linear" intercept="[amount]"/> ...
<rdar://problem/10730907>
Landed in https://trac.webkit.org/changeset/105576