To reproduce the issue: 1. Create a Sass file with last rule on line 180 or further 1. Compile Sass with debug-info 3. Load a document that references compiled CSS — the feature will be broken. Even Sass files with less than 180 and more than100 lines will display wrong line numbers be wrong. It seems that the regex on the following line replaces too much: var line = parseInt(decodeURI(match[2].replace(/(..)/g, "%$1")), 10); see http://trac.webkit.org/browser/trunk/Source/WebCore/inspector/front-end/SASSSourceMapping.js?rev=129862#L86 The regex replaces value like "3170" with "%31%70" which decodes to "1p" whereas "170" was intended. Decoding value like "%31%83" throws URIError. A simple fix seems to be to replace "/(..)/g" with "/(.)/".
Created attachment 169584 [details] Patch
Committed r131883: <http://trac.webkit.org/changeset/131883>