Fix dump debugging tools

packages/flutter/lib/src/painting/text_painter.dart

@@ -116,8 +116,9 @@ class TextSpan {
     buffer.writeln(style.toString(indent));
     if (text != null)
       buffer.writeln('$indent"$text"');
-    for (TextSpan child in children)
-      buffer.writeln(child.toString(indent));
+    if (children != null)
+      for (TextSpan child in children)
+        buffer.writeln(child.toString(indent));
     return buffer.toString();
   }
 

packages/flutter/lib/src/widgets/gesture_detector.dart

@@ -340,7 +340,7 @@ class RawGestureDetectorState extends State<RawGestureDetector> {
     if (_recognizers == null) {
       description.add('DISPOSED');
     } else {
-      List<String> gestures = _recognizers.values.map/*<String>*/((GestureRecognizer recognizer) => recognizer.toStringShort());
+      List<String> gestures = _recognizers.values.map/*<String>*/((GestureRecognizer recognizer) => recognizer.toStringShort()).toList();
       if (gestures.isEmpty)
         gestures.add('<none>');
       description.add('gestures: ${gestures.join(", ")}');