all: Apply staticcheck recommendations

transform/urlreplacers/absurlreplacer.go

@@ -37,8 +37,6 @@ type absurllexer struct {
 	quotes [][]byte
 }
 
-type stateFunc func(*absurllexer) stateFunc
-
 type prefix struct {
 	disabled bool
 	b        []byte
@@ -54,11 +52,6 @@ func newPrefixState() []*prefix {
 	}
 }
 
-type absURLMatcher struct {
-	match []byte
-	quote []byte
-}
-
 func (l *absurllexer) emit() {
 	l.w.Write(l.content[l.start:l.pos])
 	l.start = l.pos

transform/urlreplacers/absurlreplacer_test.go

@@ -41,7 +41,6 @@ const (
 	replace1 = "No replacements."
 	replace2 = "ᚠᛇᚻ ᛒᛦᚦ ᚠᚱᚩᚠᚢᚱ\nᚠᛁᚱᚪ ᚷᛖᚻᚹᛦᛚᚳᚢᛗ"
 	replace3 = `End of file: src="/`
-	replace4 = `End of file: srcset="/`
 	replace5 = `Srcsett with no closing quote: srcset="/img/small.jpg do be do be do.`
 
 	// Issue: 816, schemaless links combined with others