Update locale char when moving position in number parsing in the JSON parser.

lib/json/json.dart

Index: lib/json/json.dart
diff --git a/lib/json/json.dart b/lib/json/json.dart
index 8a0ca5cde52333ec44ab04c75cf8727031d23b98..01e30a4f36c12dd21c5c04c956682e1d132f9662 100644
--- a/lib/json/json.dart
+++ b/lib/json/json.dart
@@ -304,7 +304,7 @@ class _JsonParser {
 
     if (char === CHAR_E || char === CHAR_CAPITAL_E) {
       char = _nextChar();
-      if (char === MINUS || char === PLUS) position++;
+      if (char === MINUS || char === PLUS) char = _nextChar();
       if (_isDigit(char)) {
         char = _nextChar();
         isInt = false;