Clear document scope dirtiness in import StyleEngine.

third_party/WebKit/Source/web/tests/HTMLImportSheetsTest.cpp

 // Copyright 2017 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/dom/Document.h"
 #include "core/html/HTMLLinkElement.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "web/tests/sim/SimRequest.h"
 #include "web/tests/sim/SimTest.h"
 
 namespace blink {
 
 class HTMLImportSheetsTest : public SimTest {
  protected:
   HTMLImportSheetsTest() { WebView().Resize(WebSize(640, 480)); }
 };
 
 TEST_F(HTMLImportSheetsTest, NeedsActiveStyleUpdate) {
   SimRequest main_resource("https://example.com/", "text/html");
   SimRequest import_resource("https://example.com/import.html", "text/html");
 
   LoadURL("https://example.com/");
   main_resource.Complete("<link id=link rel=import href=import.html>");
   import_resource.Complete("<style>div{}</style>");
 
   EXPECT_TRUE(GetDocument().GetStyleEngine().NeedsActiveStyleUpdate());
+  Document* import_doc =
+      toHTMLLinkElement(GetDocument().getElementById("link"))->import();
+  ASSERT_TRUE(import_doc);
+  EXPECT_TRUE(import_doc->GetStyleEngine().NeedsActiveStyleUpdate());
+
+  GetDocument().GetStyleEngine().UpdateActiveStyle();
+
+  EXPECT_FALSE(GetDocument().GetStyleEngine().NeedsActiveStyleUpdate());
+  EXPECT_FALSE(import_doc->GetStyleEngine().NeedsActiveStyleUpdate());
 }
 
 }  // namespace blink