overflow property incorrectly stripped from symbol, image, and foreignObject elements

Created by: launchpad-issue-importer

The overflow style property is currently removed from all elements except for svg, marker, and pattern elements. This behaviour is inconsistent with http://www.w3.org/TR/2010/WD-SVG11-20100622/masking.html#OverflowProperty , which states that the overflow property applies to (in addition to marker and pattern elements), all elements that establish new viewports (see http://www.w3.org/TR/2010/WD-SVG11-20100622/coords.html#ElementsThatEstablishViewports ). Specifically, scour incorrectly strips the overflow property from symbol, image, and foreignObject elements.

Suggested fix: attached.

Imported from Launchpad using lp2gh.