Fix maximum position for spine parser recovery

This was causing all sorts of annoying and sometimes nondeterministic
problems, as it depended on the difference between the last parsed
snapshot and the current snapshot.

Editor/Parsing/XmlBackgroundParser.cs

@@ -60,7 +60,7 @@ static int MaximumCompatiblePosition (ITextSnapshot snapshotA, ITextSnapshot sna
 			while (newVersion.VersionNumber != oldVersion.VersionNumber) {
 				if (oldVersion.Changes != null) {
 					foreach (var change in oldVersion.Changes) {
-						if (change.OldPosition > position) {
+						if (change.OldPosition < position) {
 							position = change.OldPosition;
 							break;
 						}