Reuse RuntimeTypesNeedBuilderImpl and _RuntimeTypesNeed for kernel based elements

pkg/compiler/lib/src/kernel/element_map.dart

Index: pkg/compiler/lib/src/kernel/element_map.dart
diff --git a/pkg/compiler/lib/src/kernel/element_map.dart b/pkg/compiler/lib/src/kernel/element_map.dart
index 025838bb6b0f89d2866b8b14aa027487c1e65620..e06d3b3ab85338ccac615f072dbb6de6933518f8 100644
--- a/pkg/compiler/lib/src/kernel/element_map.dart
+++ b/pkg/compiler/lib/src/kernel/element_map.dart
@@ -424,6 +424,16 @@ class KernelToElementMap extends KernelElementAdapterMixin {
     return env.rawType;
   }
 
+  InterfaceType _asInstanceOf(InterfaceType type, KClass cls) {
+    OrderedTypeSet orderedTypeSet = _getOrderedTypeSet(type.element);
+    InterfaceType supertype =
+        orderedTypeSet.asInstanceOf(cls, _getHierarchyDepth(cls));
+    if (supertype != null) {
+      supertype = _substByContext(supertype, type);
+    }
+    return supertype;
+  }
+
   void _ensureSupertypes(KClass cls, _KClassEnv env) {
     if (env.orderedTypeSet == null) {
       _ensureThisAndRawType(cls, env);
@@ -901,6 +911,11 @@ class KernelElementEnvironment implements ElementEnvironment {
   }
 
   @override
+  bool isGenericClass(ClassEntity cls) {
+    return getThisType(cls).typeArguments.isNotEmpty;
+  }
+
+  @override
   DartType getTypeVariableBound(TypeVariableEntity typeVariable) {
     throw new UnimplementedError(
         'KernelElementEnvironment.getTypeVariableBound');