Elements. Remove V1 TypeDefiningElement.

Change-Id: I71ce0e198a07486f9c8b778fe642df5d7aaf73ba
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/423214
Commit-Queue: Konstantin Shcheglov <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: scheglov

pkg/analyzer/api.txt

@@ -3243,8 +3243,6 @@ package:analyzer/dart/element/element.dart:
   ShowElementCombinator (class extends Object implements NamespaceCombinator):
     new (constructor: ShowElementCombinator Function())
     shownNames (getter: List<String>)
-  TypeDefiningElement (class extends Object implements Element, deprecated):
-    new (constructor: TypeDefiningElement Function())
   UndefinedElement (class extends Object implements Element, deprecated):
     new (constructor: UndefinedElement Function())
   UriReferencedElement (class extends Object implements _ExistingElement, deprecated):

pkg/analyzer/lib/dart/element/element.dart

@@ -1180,12 +1180,6 @@ abstract class ShowElementCombinator implements NamespaceCombinator {
   List<String> get shownNames;
 }
 
-/// An element that defines a type.
-///
-/// Clients may not extend, implement or mix-in this class.
-@Deprecated('Use TypeDefiningElement2 instead')
-abstract class TypeDefiningElement implements Element {}
-
 /// A pseudo-elements that represents names that are undefined. This situation
 /// is not allowed by the language, so objects implementing this interface
 /// always represent an error. As a result, most of the normal operations on