The WidgetInspector crashes on properties with cyclic dependencies #31959
Description
The crash is caught by tests for Dart DevTools. https://travis-ci.org/flutter/devtools/jobs/527085405
The problem is 63aa5b3 started expanding properties with Diagnosticable values a bit more aggressively which exposed a bug now that some Diagnosticable objects have properties that reference other Diagnosticable objects in a cyclic way.
Server error (-32000) from ext.flutter.inspector.getChildrenDetailsSubtree():
{"exception":"Stack Overflow","stack":"#0 DiagnosticsProperty._maybeCacheValue (package:flutter/src/foundation/diagnostics.dart:2603:3)\n
#1 DiagnosticsProperty.toDescription (package:flutter/src/foundation/diagnostics.dart:2599:5)\n
#2 DiagnosticsNode.toJsonMap (package:flutter/src/foundation/diagnostics.dart:1530:22)\n
#3 DiagnosticsProperty.toJsonMap (package:flutter/src/foundation/diagnostics.dart:2475:44)\n
#4 _WidgetInspectorService._nodeToJson (package:flutter/src/widgets/widget_inspector.dart:1454:43)\n
#5 _WidgetInspectorService._nodesToJson.<anonymous closure>