Move kernel baseline tests to front_end.

pkg/front_end/testcases/escape.dart.outline.expect

 library;
 import self as self;
 import "dart:core" as core;
 
 class A extends core::Object {
+  field dynamic field;
   constructor •() → void
     ;
 }
 class B extends core::Object {
+  field dynamic field;
   constructor •() → void
     ;
 }
 class C extends core::Object {
   constructor •() → void
     ;
+  operator ==(dynamic x) → dynamic
+    ;
 }
-class D extends core::Object {
+class X extends core::Object implements self::A, self::B {
+  field dynamic field;
   constructor •() → void
     ;
 }
+static method useAsA(self::A object) → void
+  ;
+static method useAsB(self::B object) → void
+  ;
+static method escape(dynamic x) → void
+  ;
 static method main() → dynamic
   ;