Don't add to siblingRules for features left of ::slotted.

third_party/WebKit/Source/core/css/RuleFeatureSetTest.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/css/RuleFeature.h"
 
 #include "core/css/CSSSelectorList.h"
 #include "core/css/RuleSet.h"
 #include "core/css/StylePropertySet.h"
 #include "core/css/StyleRule.h"
@@ skipping 339 matching lines @@
     collectInvalidationSetsForClass(invalidationLists, "a");
     expectClassesInvalidation("b", "c", invalidationLists.descendants);
 }
 
 TEST_F(RuleFeatureSetTest, siblingRulesBeforeContentPseudo)
 {
     collectFeatures("a + b ::content .c");
     expectSiblingRuleCount(0);
 }
 
+TEST_F(RuleFeatureSetTest, siblingRulesBeforeContentPseudo2)
+{
+    collectFeatures("a + ::content .b");
+    expectSiblingRuleCount(0);
+}
+
 TEST_F(RuleFeatureSetTest, siblingRulesAfterContentPseudo)
 {
     collectFeatures(".a ::content .b + .c");
     expectSiblingRuleCount(1);
 }
 
 TEST_F(RuleFeatureSetTest, siblingRulesNthBeforeContentPseudo)
 {
     collectFeatures(":nth-child(2) ::content .a");
     expectSiblingRuleCount(0);
@@ skipping 25 matching lines @@
 
 TEST_F(RuleFeatureSetTest, siblingRulesAfterShadow)
 {
     collectFeatures(".a ::shadow .b + .c");
     expectSiblingRuleCount(1);
 }
 
 TEST_F(RuleFeatureSetTest, siblingRulesBeforeSlotted)
 {
     collectFeatures(".a + ::slotted(.b)");
-    expectSiblingRuleCount(1);
+    expectSiblingRuleCount(0);
+}
+
+TEST_F(RuleFeatureSetTest, siblingRulesBeforeHost)
+{
+    collectFeatures(".a + :host(.b)");
+    expectSiblingRuleCount(0);
+}
+
+TEST_F(RuleFeatureSetTest, siblingRulesBeforeHostContext)
+{
+    collectFeatures(".a + :host-context(.b)");
+    expectSiblingRuleCount(0);
 }
 
 } // namespace blink