CSS: Avoid invalidating style when only descendants need updating

LayoutTests/fast/css/invalidation/compound.html

Index: LayoutTests/fast/css/invalidation/compound.html
diff --git a/LayoutTests/fast/css/invalidation/compound.html b/LayoutTests/fast/css/invalidation/compound.html
index 80651a0dd8136a8f1845a5997f0dc72e2ad90a1b..c049b98ecb90f98f8d467ff7645c770225c0140b 100644
--- a/LayoutTests/fast/css/invalidation/compound.html
+++ b/LayoutTests/fast/css/invalidation/compound.html
@@ -130,7 +130,7 @@ test(function() {
     assert_equals(getComputedStyle(r1).backgroundColor, "rgba(0, 0, 0, 0)", "Background color should initially be transparent");
 
     t1.className = "t1";
-    assert_equals(internals.updateStyleAndReturnAffectedElementCount(), 5, "Subtree style recalc");
+    assert_equals(internals.updateStyleAndReturnAffectedElementCount(), 4, "Subtree style recalc");
     assert_equals(getComputedStyle(r1).backgroundColor, "rgb(0, 128, 0)", "Background color is green after class change");
 }, "Descendant with compound selector containing id");
 
@@ -138,7 +138,7 @@ test(function() {
     assert_equals(getComputedStyle(r2).backgroundColor, "rgba(0, 0, 0, 0)", "Background color should initially be transparent");
 
     t2.className = "t2";
-    assert_equals(internals.updateStyleAndReturnAffectedElementCount(), 3, "Subtree style recalc");
+    assert_equals(internals.updateStyleAndReturnAffectedElementCount(), 2, "Subtree style recalc");
     assert_equals(getComputedStyle(r2).backgroundColor, "rgb(0, 128, 0)", "Background color is green after class change");
 }, "Descendant with compound selector containing universal and id");
 
@@ -146,7 +146,7 @@ test(function() {
     assert_equals(getComputedStyle(r3).backgroundColor, "rgba(0, 0, 0, 0)", "Background color should initially be transparent");
 
     t3.className = "t3";
-    assert_equals(internals.updateStyleAndReturnAffectedElementCount(), 4, "Subtree style recalc");
+    assert_equals(internals.updateStyleAndReturnAffectedElementCount(), 3, "Subtree style recalc");
     assert_equals(getComputedStyle(r3).backgroundColor, "rgb(0, 128, 0)", "Background color is green after class change");
 }, "Descendant with compound selector");
 
@@ -154,7 +154,7 @@ test(function() {
     assert_equals(getComputedStyle(r4).backgroundColor, "rgba(0, 0, 0, 0)", "Background color should initially be transparent");
 
     t4.className = "t4";
-    assert_equals(internals.updateStyleAndReturnAffectedElementCount(), 4, "Subtree style recalc");
+    assert_equals(internals.updateStyleAndReturnAffectedElementCount(), 3, "Subtree style recalc");
     assert_equals(getComputedStyle(r4).backgroundColor, "rgb(0, 128, 0)", "Background color is green after class change");
 }, "Descendant with compound selector containing universal");
 
@@ -163,7 +163,7 @@ test(function() {
     assert_equals(getComputedStyle(r5b).backgroundColor, "rgba(0, 0, 0, 0)", "Background color b should initially be transparent");
 
     t5.className = "t5";
-    assert_equals(internals.updateStyleAndReturnAffectedElementCount(), 6, "Subtree style recalc");
+    assert_equals(internals.updateStyleAndReturnAffectedElementCount(), 5, "Subtree style recalc");
     assert_equals(getComputedStyle(r5a).backgroundColor, "rgb(0, 128, 0)", "Background color a is green after class change");
     assert_equals(getComputedStyle(r5b).backgroundColor, "rgb(0, 128, 0)", "Background color b is green after class change");
 }, "Descendant with :-webkit-any containing compound selector");