[vm] Fix crashes on record types in mirrors and observatory

TEST=ci, manually verified tests with https://dart-review.googlesource.com/c/sdk/+/290760.

Fixes https://github.com/dart-lang/sdk/issues/51900

Change-Id: I338bc1b1f2e58d2343f6195ff9d12151edbd90dc
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/291969
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Ben Konyi <bkonyi@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>

runtime/lib/mirrors.cc

@@ -530,6 +530,12 @@ static InstancePtr CreateTypeMirror(const AbstractType& type) {
   if (type.IsFunctionType()) {
     return CreateFunctionTypeMirror(type);
   }
+  if (type.IsRecordType()) {
+    const Class& cls =
+        Class::Handle(IsolateGroup::Current()->object_store()->record_class());
+    return CreateClassMirror(cls, AbstractType::Handle(cls.DeclarationType()),
+                             Bool::False(), Object::null_instance());
+  }
   if (type.HasTypeClass()) {
     const Class& cls = Class::Handle(type.type_class());
     // Handle void and dynamic types.

runtime/observatory/lib/src/service/object.dart

@@ -2782,9 +2782,9 @@ M.InstanceKind stringToInstanceKind(String s) {
       return M.InstanceKind.typeRef;
     case 'ReceivePort':
       return M.InstanceKind.receivePort;
-    case '_RecordType':
+    case 'RecordType':
       return M.InstanceKind.recordType;
-    case '_Record':
+    case 'Record':
       return M.InstanceKind.record;
     case 'Finalizer':
       return M.InstanceKind.finalizer;