Fix boolean logic error

I thought that this would result in the following if-block executing, as
needed to pass the test case in the previous commit. However, it appears
that it's not actually needed to pass the test case, since `makeString`
doesn't unescape unnecessarily escaped non-quote characters.
Nevertheless, I think we should leave that if-block (`if (canChangeDirectiveQuotes)`)
there, in case `makeString` is updated.

See #1571 (comment)

src/printer.js

@@ -3876,7 +3876,7 @@ function nodeStr(node, options) {
   // change the escape sequences they use.
   // See https://github.com/prettier/prettier/issues/1555
   // and https://tc39.github.io/ecma262/#directive-prologue
-  if (isDirectiveLiteral && !canChangeDirectiveQuotes) {
+  if (isDirectiveLiteral) {
     if (canChangeDirectiveQuotes) {
       return enclosingQuote + rawContent + enclosingQuote;
     } else {