Remove work-around for analyzer issue that is now fixed

Related to dart-lang/sdk#29767

Author: kevmoo

lib/src/type_checker.dart

@@ -125,7 +125,8 @@ abstract class TypeChecker {
 
   /// Returns `true` if the type of [element] can be assigned to this type.
   bool isAssignableFrom(Element element) =>
-      isExactly(element) || _getAllSupertypes(element).any(isExactlyType);
+      isExactly(element) ||
+      (element is ClassElement && element.allSupertypes.any(isExactlyType));
 
   /// Returns `true` if [staticType] can be assigned to this type.
   bool isAssignableFromType(DartType staticType) =>
@@ -164,29 +165,6 @@ abstract class TypeChecker {
   bool isSuperTypeOf(DartType staticType) => isSuperOf(staticType.element);
 }
 
-// TODO(kevmoo) Remove when bug with `ClassElement.allSupertypes` is fixed
-// https://github.com/dart-lang/sdk/issues/29767
-Iterable<InterfaceType> _getAllSupertypes(Element element) sync* {
-  if (element is ClassElement) {
-    var processed = new Set<InterfaceType>();
-    var toExplore = new List<InterfaceType>.from(element.allSupertypes);
-
-    while (toExplore.isNotEmpty) {
-      var item = toExplore.removeLast();
-
-      if (processed.add(item)) {
-        yield item;
-
-        // Now drill into nested superTypes - but make sure not to duplicate
-        // any of them.
-        toExplore.addAll(item.element.allSupertypes.where((e) {
-          return !toExplore.contains(e) && !processed.contains(e);
-        }));
-      }
-    }
-  }
-}
-
 // Checks a static type against another static type;
 class _LibraryTypeChecker extends TypeChecker {
   final DartType _type;

pubspec.yaml

@@ -1,12 +1,12 @@
 name: source_gen
-version: 0.7.5+1
+version: 0.7.6-dev
 author: Dart Team <[email protected]>
 description: Automated source code generation for Dart.
 homepage: https://github.com/dart-lang/source_gen
 environment:
   sdk: '>=2.0.0-dev.19.0 <2.0.0'
 dependencies:
-  analyzer: '>=0.29.10 <0.32.0'
+  analyzer: ^0.31.0
   build: '>=0.10.0 <0.13.0'
   dart_style: '>=0.1.7 <2.0.0'
   meta: ^1.1.0