Update error-handling for fe*Lighting and feTurbulence

Invalid parameters now produce transparent black rather than failing the
build step.
The new behavior matches Gecko for fe*Lighting but not for feTurbulence
(where they seem to allow negative baseFrequency values), so in the
latter case we're siding with the "Negative values are unsupported"
wording in the spec[1].

[1] https://drafts.fxtf.org/filters/#element-attrdef-feturbulence-basefrequency

BUG=533457

Review URL: https://codereview.chromium.org/1375793003

Cr-Commit-Position: refs/heads/master@{#351817}
15 files changed