Support invalidation sets for :host pseudo.

LayoutTests/fast/css/invalidation/targeted-class-host-pseudo-expected.txt

Index: LayoutTests/fast/css/invalidation/targeted-class-host-pseudo-expected.txt
diff --git a/LayoutTests/fast/css/invalidation/targeted-class-host-pseudo-expected.txt b/LayoutTests/fast/css/invalidation/targeted-class-host-pseudo-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..88349e1d7d4699184922491e89a0922035a1fa49
--- /dev/null
+++ b/LayoutTests/fast/css/invalidation/targeted-class-host-pseudo-expected.txt
@@ -0,0 +1,21 @@
+Check that targeted class invalidation works with the :host pseudo class.
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+PASS getComputedStyle(host1, null).backgroundColor is transparent
+PASS getComputedStyle(inner, null).backgroundColor is transparent
+PASS getComputedStyle(host3, null).backgroundColor is transparent
+PASS getComputedStyle(host4, null).backgroundColor is transparent
+PASS internals.updateStyleAndReturnAffectedElementCount() is 1
+PASS getComputedStyle(host1, null).backgroundColor is green
+PASS internals.updateStyleAndReturnAffectedElementCount() is 2
+PASS getComputedStyle(inner, null).backgroundColor is green
+PASS internals.updateStyleAndReturnAffectedElementCount() is 6
+PASS getComputedStyle(host3, null).backgroundColor is green
+PASS internals.updateStyleAndReturnAffectedElementCount() is 1
+PASS getComputedStyle(host4, null).backgroundColor is green
+PASS successfullyParsed is true
+
+TEST COMPLETE
+