Print static types of conditional expressions.

pkg/front_end/testcases/micro.dart.strong.expect

 library;
 import self as self;
 import "dart:core" as core;
 
 class Foo extends core::Object {
   constructor •() → void
     : super core::Object::•()
     ;
   method instanceMethod() → dynamic {
     return 123;
   }
 }
 abstract class ExternalValue extends core::Object {
+  constructor •() → void
+    : super core::Object::•()
+    ;
 }
 abstract class Bar extends core::Object {
+  constructor •() → void
+    : super core::Object::•()
+    ;
   abstract method externalInstanceMethod() → self::ExternalValue;
 }
 class Box extends core::Object {
   field dynamic field = null;
   constructor •() → void
     : super core::Object::•()
     ;
 }
 class FinalBox extends core::Object {
   final field dynamic finalField;
@@ skipping 14 matching lines @@
 }
 class DynamicReceiver2 extends core::Object {
   constructor •() → void
     : super core::Object::•()
     ;
   method dynamicallyCalled(dynamic x) → dynamic {}
 }
 static method staticMethod() → dynamic {
   return "sdfg";
 }
-external static method externalStatic() → core::bool;
-external static method createBar() → self::Bar;
+external static abstract method externalStatic() → core::bool;
+external static abstract method createBar() → self::Bar;
 static method stringArgument(dynamic x) → dynamic {}
 static method intArgument(dynamic x) → dynamic {}
 static method makeDynamicCall(dynamic receiver) → void {
   receiver.dynamicallyCalled("sdfg");
 }
 static method main() → dynamic {
   dynamic x = self::staticMethod();
   dynamic y = new self::Foo::•().{self::Foo::instanceMethod}();
   core::bool z = self::externalStatic();
   self::ExternalValue w = self::createBar().{self::Bar::externalInstanceMethod}();
   self::stringArgument("sdfg");
   self::intArgument(42);
   self::Box box = new self::Box::•();
   box.{self::Box::field} = "sdfg";
   dynamic a = box.{self::Box::field};
   self::FinalBox finalBox = new self::FinalBox::•("dfg");
   dynamic b = finalBox.{self::FinalBox::finalField};
   self::SubFinalBox subBox = new self::SubFinalBox::•("dfg");
   dynamic c = subBox.{self::FinalBox::finalField};
   self::makeDynamicCall(new self::DynamicReceiver1::•());
   self::makeDynamicCall(new self::DynamicReceiver2::•());
   core::List<core::String> list = <core::String>["string"];
   core::String d = list.{core::List::[]}(0);
 }