core, trie: replace state caches with trie journal

trie/proof.go

@@ -70,15 +70,13 @@ func (t *Trie) Prove(key []byte) []rlp.RawValue {
 			panic(fmt.Sprintf("%T: invalid node: %v", tn, tn))
 		}
 	}
-	if t.hasher == nil {
-		t.hasher = newHasher()
-	}
+	hasher := newHasher()
 	proof := make([]rlp.RawValue, 0, len(nodes))
 	for i, n := range nodes {
 		// Don't bother checking for errors here since hasher panics
 		// if encoding doesn't work and we're not writing to any database.
-		n, _, _ = t.hasher.hashChildren(n, nil)
-		hn, _ := t.hasher.store(n, nil, false)
+		n, _, _ = hasher.hashChildren(n, nil)
+		hn, _ := hasher.store(n, nil, false)
 		if _, ok := hn.(hashNode); ok || i == 0 {
 			// If the node's database encoding is a hash (or is the
 			// root node), it becomes a proof element.