Fix empty range for ternary question mark (#215)

skip() was used after the qmark token, which resets the start position:
https://github.com/tree-sitter/tree-sitter/blob/9df064c9fe31d35dc48244a6675588aee2d61a41/lib/src/lexer.c#L184

Author: tom95

common/scanner.h

@@ -172,19 +172,19 @@ static bool scan_ternary_qmark(TSLexer *lexer) {
     /* Optional chaining. */
     if (lexer->lookahead == '.') return false;
 
+    lexer->mark_end(lexer);
+    lexer->result_symbol = TERNARY_QMARK;
+
     /* TypeScript optional arguments contain the ?: sequence, possibly
        with whitespace. */
     for(;;) {
       if (!iswspace(lexer->lookahead)) break;
-      skip(lexer);
+      advance(lexer);
     }
     if (lexer->lookahead == ':') return false;
     if (lexer->lookahead == ')') return false;
     if (lexer->lookahead == ',') return false;
 
-    lexer->mark_end(lexer);
-    lexer->result_symbol = TERNARY_QMARK;
-
     if (lexer->lookahead == '.') {
       advance(lexer);
       if (iswdigit(lexer->lookahead)) return true;