Dart `_HashMap` class does not show the same debugger view as map

To fix this and similar cases such as _HashSet and perhaps all classes implementing Map, Set, and Iterable
we should add helpers to Dart DevTools that use helpers to efficiently extra out the values from these fields by doing a single eval to convert over to the correct Dart List data to batch read the values.
Screenshot showing how this makes it hard to see the _inheritedWidgets for a Flutter class.

No file or test is named. Start by locating the Dart DevTools debugger handling for _HashMap and its collection views, then review how a single evaluation could batch-read values. Done means _HashMap, _HashSet, and applicable Map, Set, or Iterable implementations expose useful debugger views, including the _inheritedWidgets case.

Scritto dal modello di indicizzazione a partire dal testo della issue.