NNBD migrator: record type information in TypeName type arguments

This prevents the following crash:

Bad state: Missing declarated type annotation in /home/test/lib/test.dart; for Object
  package:nnbd_migration/src/variables.dart 68:7                      Variables.decoratedTypeAnnotation
  package:nnbd_migration/src/edge_builder.dart 1378:26                EdgeBuilder.visitTypeName
  package:analyzer/src/dart/ast/ast.dart 10012:49                     TypeNameImpl.accept
  package:nnbd_migration/src/edge_builder.dart 844:10                 EdgeBuilder.visitIsExpression
  package:analyzer/src/dart/ast/ast.dart 6372:49                      IsExpressionImpl.accept

Change-Id: I23ed49ccbd3625d9f9fbc7e07a69be3c580896ff
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/127457
Commit-Queue: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Paul Berry <paulberry@google.com>

pkg/nnbd_migration/lib/src/node_builder.dart

@@ -253,7 +253,7 @@ class NodeBuilder extends GeneralizingAstVisitor<DecoratedType>
     try {
       node.typeParameters?.accept(this);
       node.parameters?.accept(this);
-      // Node: we don't pass _typeFormalBounds into DecoratedType because we're
+      // Note: we don't pass _typeFormalBounds into DecoratedType because we're
       // not defining a generic function type, we're defining a generic typedef
       // of an ordinary (non-generic) function type.
       decoratedFunctionType = DecoratedType(functionType, _graph.never,
@@ -398,6 +398,7 @@ class NodeBuilder extends GeneralizingAstVisitor<DecoratedType>
     }
     DecoratedType decoratedType;
     if (type is FunctionType && node is! GenericFunctionType) {
+      (node as TypeName).typeArguments?.accept(this);
       // node is a reference to a typedef.  Treat it like an inferred type (we
       // synthesize new nodes for it).  These nodes will be unioned with the
       // typedef nodes by the edge builder.

pkg/nnbd_migration/test/edge_builder_test.dart

@@ -2332,6 +2332,15 @@ int/*2*/ g() {
             hard: false));
   }
 
+  test_functionTypeAlias_inExpression() async {
+    await analyze('''
+typedef bool _P<T>(T value);
+bool f(Object x) => x is _P<Object>;
+''');
+    // No assertions here; just don't crash. This test can be repurposed for
+    // a more specific test with assertions.
+  }
+
   test_genericMethodInvocation() async {
     await analyze('''
 class Base {
@@ -2400,6 +2409,15 @@ int bar(Derived<String> d, int i, List<String> j) => d.foo(i, j);
         hard: false);
   }
 
+  test_genericTypeAlias_inExpression() async {
+    await analyze('''
+typedef _P<T> = bool Function(T value);
+bool f(Object x) => x is _P<Object>;
+''');
+    // No assertions here; just don't crash. This test can be repurposed for
+    // a more specific test with assertions.
+  }
+
   test_if_condition() async {
     await analyze('''
 void f(bool b) {