In FEColorMatrix.cpp, the 'offset' matrix values (the fifth column in the matrix) are not used to calculate the result of a color transformation. The correct matrix multiplication is stated here: http://www.w3.org/TR/SVG/filters.html#feColorMatrixElement.
Created attachment 75906 [details] Testcase for feColorMatrix using offsets
Created attachment 76037 [details] Proposed patch
Looks good to me, adding Dirk to review.
Comment on attachment 76037 [details] Proposed patch r=me. Sorry for the late response.
Comment on attachment 76037 [details] Proposed patch Clearing flags on attachment: 76037 Committed r74010: <http://trac.webkit.org/changeset/74010>
All reviewed patches have been landed. Closing bug.