Consider the testcase in the url field. In WebKit this renders with the input stretching the full width of the viewport. Per CSS 2.1 section 10.3.8, the width should be the width a text input would normally have (rule 1 in 10.3.8), and the 'right' value should be ignored because the values are over-constrained (rule 6 in 10.3.8).
WebKit gets this right for images, but not for text inputs.
Gecko, Presto, and Trident all do this right.