Remove additive classifications when generating ClassifiedText from ClassifiedSpans

src/VisualStudio/Core/Def/Implementation/FindReferences/Entries/DocumentSpanEntry.cs

@@ -69,7 +69,12 @@ protected override IList<System.Windows.Documents.Inline> CreateLineTextInlines(
                                           .GetProperties(propertyId);
                 var highlightBrush = properties["Background"] as Brush;
 
-                var classifiedSpans = _excerptResult.ClassifiedSpans;
+                // Remove additive classified spans before creating classified text.
+                // Otherwise the text will be repeated since there are two classifications
+                // for the same span. Additive classifications should not change the foreground
+                // color, so the resulting classified text will retain the proper look.
+                var classifiedSpans = _excerptResult.ClassifiedSpans.WhereAsArray(
+                    cs => !ClassificationTypeNames.AdditiveTypeNames.Contains(cs.ClassificationType));
                 var classifiedTexts = classifiedSpans.SelectAsArray(
                     cs => new ClassifiedText(cs.ClassificationType, _excerptResult.Content.ToString(cs.TextSpan)));