Hide internal implementation details in type objects

[annagrin]

In this PR:

• Modify class metadata to determine an object's runtime type kind
• Modify instance.dart to convert from runtime objects to instances better
  • show types concisely
    • all types are shown as instances of core:Type class
    • print the type name correctly
    • no internal type representation details
    • matches vm display of types
  • show native JavaScript types and errors as objects of their type
• Move getProperties from debugger to inspector
  • cache runtime kinds of classRefs to support better runtime object type detection
• Add type inspection tests

Before

After

VSCode (consistent with VM)

DevTools (consistent with VM)

Closes: #2086
Towards: #1949

[nshahan]

What does RuntimeObjectKind.wrappedType represent in this context? There might be a different name that causes less confusion.

I really dislike how DDC uses the term "WrappedType" because it always leads to confusion when discussing the types. We have an internal type that is used for all type operations. When we need to return a value from .runtimeType calls we pass our internal type object to a method called wrapType() that returns a Dart Type object that wraps the internal representation. Then in various comments we refer to the wrapping Type object as the "wrapped type". It continually confuses me because I also tend to think of the type inside as the "wrapped type" because it has a wrapper around it. Good news is that all of this is on the list to be deleted when we switch type systems.

[annagrin]

It is the dart._Type object we get from DDC on x.runtimeType calls. It has an _type field with the actual DartType. Other runtime kinds (RuntimeObjectKind.type and RuntimeObjectKind.recordType) are for the internal types (RecordType, class types, and primitive types objects). Would ExternalType or TypeWrapper work better than WrappedType?

[annagrin]

Replaced by TypeWrapper, to make the 'container' intention clearer.

[annagrin]

Actually, I realized I can optimize the type wrapper case away (by unrolling the recursion in JS code for getting metadata), and minimize the number of wrapType calls. Updated.

[bkonyi]

Generally LGTM, but I'll let a DWDS maintainer give final approval :-)

[nshahan]

LGTM with the minor changes from our discussion today.