Prepare IsFocused test for parser blocking sheets.

Test relied on html parsing continuing before sheet in head was loaded.
That is not the case with BlockHTMLParserOnStyleSheets enabled.

Bug: 891767
Change-Id: Iec83d26fd55cd8e667ba7b321e7f89cca16597fe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1928784Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718566}

third_party/blink/renderer/core/exported/web_node_test.cc

@@ -14,6 +14,7 @@
 #include "third_party/blink/renderer/core/testing/page_test_base.h"
 #include "third_party/blink/renderer/core/testing/sim/sim_request.h"
 #include "third_party/blink/renderer/core/testing/sim/sim_test.h"
+#include "third_party/blink/renderer/platform/testing/unit_test_helpers.h"
 
 namespace blink {
 
@@ -76,13 +77,20 @@ TEST_F(WebNodeSimTest, IsFocused) {
 
   css_resource.Start();
 
-  EXPECT_TRUE(GetDocument().GetStyleEngine().HasPendingRenderBlockingSheets());
-
   WebNode input_node(GetDocument().getElementById("focusable"));
   EXPECT_FALSE(input_node.IsFocusable());
+  EXPECT_EQ(!RuntimeEnabledFeatures::BlockHTMLParserOnStyleSheetsEnabled(),
+            GetDocument().GetStyleEngine().HasPendingRenderBlockingSheets());
 
   main_resource.Finish();
   css_resource.Complete("dummy {}");
+  test::RunPendingTasks();
+
+  if (RuntimeEnabledFeatures::BlockHTMLParserOnStyleSheetsEnabled()) {
+    // Need to re-initialize the WebNode since it was null on construction.
+    EXPECT_TRUE(input_node.IsNull());
+    input_node = GetDocument().getElementById("focusable");
+  }
   EXPECT_TRUE(input_node.IsFocusable());
 }