Delete Sky tests that we're not going to run with Dart

sky/tests/mutation-observer/observe-childList-expected.txt

Index: sky/tests/mutation-observer/observe-childList-expected.txt
diff --git a/sky/tests/mutation-observer/observe-childList-expected.txt b/sky/tests/mutation-observer/observe-childList-expected.txt
deleted file mode 100644
index ad35d53d38f684446f664d9199c3d402650b6225..0000000000000000000000000000000000000000
--- a/sky/tests/mutation-observer/observe-childList-expected.txt
+++ /dev/null
@@ -1,11 +0,0 @@
-Running 7 tests
-ok 1 MutationObserver.observe on childList should handle basic observation
-ok 2 MutationObserver.observe on childList should handle observing without specifying "childList" does not result in hearing about childList changes
-ok 3 MutationObserver.observe on childList should handle re-observing the same node with the same observer has the effect of resetting the options
-ok 4 MutationObserver.observe on childList should handle multiple observers can be registered to a given node and both receive mutations
-ok 5 MutationObserver.observe on childList should create minimal mutations for replaceChild
-ok 6 MutationObserver.observe on childList should create minimal mutations for insertBefore
-ok 7 MutationObserver.observe on childList should create minimal mutations for appendChild
-7 tests
-7 pass
-0 fail