fixed a JSON bug with handling backspaces

This was fixed in upstream and the upstream tests caught this :-)

inc/JSON.php

@@ -569,17 +569,17 @@ class JSON {
 
                             }
 
-                        } elseif ((($chrs{$c} == '"') || ($chrs{$c} == "'")) &&
-                                 in_array($top['what'], array(JSON_SLICE, JSON_IN_ARR, JSON_IN_OBJ))) {
+                        } elseif ((($chrs{$c} == '"') || ($chrs{$c} == "'")) && ($top['what'] != JSON_IN_STR)) {
                             // found a quote, and we are not inside a string
                             array_push($stk, array('what' => JSON_IN_STR, 'where' => $c, 'delim' => $chrs{$c}));
                             //print("Found start of string at {$c}\n");
 
                         } elseif (($chrs{$c} == $top['delim']) &&
                                  ($top['what'] == JSON_IN_STR) &&
-                                 (($chrs{$c - 1} != "\\") ||
-                                 ($chrs{$c - 1} == "\\" && $chrs{$c - 2} == "\\"))) {
+                                 ((strlen(substr($chrs, 0, $c)) - strlen(rtrim(substr($chrs, 0, $c), '\\'))) % 2 != 1)) {
                             // found a quote, we're in a string, and it's not escaped
+                            // we know that it's not escaped becase there is _not_ an
+                            // odd number of backslashes at the end of the string so far
                             array_pop($stk);
                             //print("Found end of string at {$c}: ".substr($chrs, $top['where'], (1 + 1 + $c - $top['where']))."\n");