Switch to lifenjoiner's ewma variant

vendor/golang.org/x/mod/modfile/read.go

@@ -194,15 +194,12 @@ func (x *FileSyntax) updateLine(line *Line, tokens ...string) {
 	line.Token = tokens
 }
 
-// markRemoved modifies line so that it (and its end-of-line comment, if any)
-// will be dropped by (*FileSyntax).Cleanup.
-func (line *Line) markRemoved() {
+func (x *FileSyntax) removeLine(line *Line) {
 	line.Token = nil
-	line.Comments.Suffix = nil
 }
 
 // Cleanup cleans up the file syntax x after any edit operations.
-// To avoid quadratic behavior, (*Line).markRemoved marks the line as dead
+// To avoid quadratic behavior, removeLine marks the line as dead
 // by setting line.Token = nil but does not remove it from the slice
 // in which it appears. After edits have all been indicated,
 // calling Cleanup cleans out the dead lines.