Move kernel baseline tests to front_end.

pkg/kernel/testcases/spec-mode/null_aware.baseline.txt

Index: pkg/kernel/testcases/spec-mode/null_aware.baseline.txt
diff --git a/pkg/kernel/testcases/spec-mode/null_aware.baseline.txt b/pkg/kernel/testcases/spec-mode/null_aware.baseline.txt
deleted file mode 100644
index 9a60a6263ef7d525e8e2683185e96815c77a0250..0000000000000000000000000000000000000000
--- a/pkg/kernel/testcases/spec-mode/null_aware.baseline.txt
+++ /dev/null
@@ -1,22 +0,0 @@
-library;
-import self as self;
-import "dart:core" as core;
-
-class Foo extends core::Object {
-  field core::int field = null;
-  static field core::int staticField = null;
-  constructor •() → void
-    : super core::Object::•()
-    ;
-}
-static method main() → dynamic {
-  self::Foo foo = new self::Foo::•();
-  let final dynamic #t1 = foo in #t1.==(null) ? null : #t1.field = 5;
-  self::Foo::staticField = 5;
-  let final dynamic #t2 = foo in #t2.field.==(null) ? #t2.field = 5 : null;
-  self::Foo::staticField.==(null) ? self::Foo::staticField = 5 : null;
-  let final dynamic #t3 = foo in #t3.==(null) ? null : #t3.field.==(null) ? #t3.field = 5 : null;
-  self::Foo::staticField.==(null) ? self::Foo::staticField = 5 : null;
-  core::int intValue = let final dynamic #t4 = foo.field in #t4.==(null) ? 6 : #t4;
-  core::num numValue = let final dynamic #t5 = foo.field in #t5.==(null) ? 4.5 : #t5;
-}