Fix virtual scroller WPT tests and reenable most of them.

There were multiple problems:

- the tests all passed all the time because displayLocking was
  disabled, so nothing ever got locked (crbug.com/986574)

- the content of the test files was incorrect, they were all executing
  the same test entry from ref-tests.js (looks like the last patchset
  overwrote them all, https://chromium-review.googlesource.com/c/chromium/src/+/1680170/35..36 .

- the scroller takes several frames to full unlock the correct
  elements, so this change adds a 1s delay to give it time.

- the part.html test is actually failing crbug.com/998356 and so
  remains disabled for now.

BUG=986574

Change-Id: I443ad7a1ce1eb6fd3d8c227e4635ceec0ebcd81e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1772951Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Fergal Daly <fergal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#691043}

third_party/blink/web_tests/TestExpectations

@@ -251,7 +251,7 @@ crbug.com/991095 wpt_internal/display-lock/rendersubtree/acquire-clone.html [ Fa
 crbug.com/996625 inspector-protocol/accessibility/accessibility-getFullAXTree-display-locked.js [ Skip ]
 
 # virtual-scroller failures
-crbug.com/986574 wpt_internal/virtual-scroller/ [ Failure ]
+crbug.com/998356 wpt_internal/virtual-scroller/part.html [ Failure ]
 
 # Sheriff 2018/05/25
 crbug.com/846747 http/tests/navigation/navigation-interrupted-by-fragment.html  [ Pass Timeout ]

third_party/blink/web_tests/wpt_internal/virtual-scroller/full-ref.html

@@ -3,6 +3,6 @@
   <style>body { overflow:hidden; }</style>
   <script type="module">
     import * as refTests from './resources/ref-tests.mjs';
-    refTests.withDiv(refTests.testFullScroll500px);
+    refTests.withDiv(refTests.testFull);
   </script>
 </html>

third_party/blink/web_tests/wpt_internal/virtual-scroller/full.html

@@ -4,10 +4,10 @@
   <title>Creates more than a screenful of divs.</title>
   <style>body { overflow:hidden; }</style>
   <link rel="author" title="Fergal Daly" href="mailto:fergal@chromium.org">
-  <link rel="match" href="full-scroll-500px-ref.html">
+  <link rel="match" href="full-ref.html">
   <script type="module">
     import 'std:elements/virtual-scroller';
     import * as refTests from './resources/ref-tests.mjs';
-    refTests.withVirtualScroller(refTests.testFullScroll500px);
+    refTests.withVirtualScroller(refTests.testFull);
   </script>
 </html>

third_party/blink/web_tests/wpt_internal/virtual-scroller/move-element-ref.html

@@ -3,6 +3,6 @@
   <style>body { overflow:hidden; }</style>
   <script type="module">
     import * as refTests from './resources/ref-tests.mjs';
-    refTests.withDiv(refTests.testFullScroll500px);
+    refTests.withDiv(refTests.testMoveElement);
   </script>
 </html>

third_party/blink/web_tests/wpt_internal/virtual-scroller/move-element-scroll-into-view-ref.html

@@ -3,6 +3,6 @@
   <style>body { overflow:hidden; }</style>
   <script type="module">
     import * as refTests from './resources/ref-tests.mjs';
-    refTests.withDiv(refTests.testFullScroll500px);
+    refTests.withDiv(refTests.testMoveElementScrollIntoView);
   </script>
 </html>

third_party/blink/web_tests/wpt_internal/virtual-scroller/move-element-scroll-into-view.html

@@ -7,10 +7,10 @@
   </title>
   <style>body { overflow:hidden; }</style>
   <link rel="author" title="Fergal Daly" href="mailto:fergal@chromium.org">
-  <link rel="match" href="full-scroll-500px-ref.html">
+  <link rel="match" href="move-element-scroll-into-view-ref.html">
   <script type="module">
     import 'std:elements/virtual-scroller';
     import * as refTests from './resources/ref-tests.mjs';
-    refTests.withVirtualScroller(refTests.testFullScroll500px);
+    refTests.withVirtualScroller(refTests.testMoveElementScrollIntoView);
   </script>
 </html>

third_party/blink/web_tests/wpt_internal/virtual-scroller/move-element.html

@@ -4,10 +4,10 @@
   <title>Creates more than a screenful of divs and moves the first to the end.</title>
   <style>body { overflow:hidden; }</style>
   <link rel="author" title="Fergal Daly" href="mailto:fergal@chromium.org">
-  <link rel="match" href="full-scroll-500px-ref.html">
+  <link rel="match" href="move-element-ref.html">
   <script type="module">
     import 'std:elements/virtual-scroller';
     import * as refTests from './resources/ref-tests.mjs';
-    refTests.withVirtualScroller(refTests.testFullScroll500px);
+    refTests.withVirtualScroller(refTests.testMoveElement);
   </script>
 </html>

third_party/blink/web_tests/wpt_internal/virtual-scroller/part-ref.html

@@ -3,6 +3,6 @@
   <style>body { overflow:hidden; }</style>
   <script type="module">
     import * as refTests from './resources/ref-tests.mjs';
-    refTests.withDiv(refTests.testFullScroll500px);
+    refTests.withDiv(refTests.testPart);
   </script>
 </html>

third_party/blink/web_tests/wpt_internal/virtual-scroller/part.html

@@ -4,10 +4,10 @@
   <title>Creates less than a screenful of divs.</title>
   <style>body { overflow:hidden; }</style>
   <link rel="author" title="Fergal Daly" href="mailto:fergal@chromium.org">
-  <link rel="match" href="full-scroll-500px-ref.html">
+  <link rel="match" href="part-ref.html">
   <script type="module">
     import 'std:elements/virtual-scroller';
     import * as refTests from './resources/ref-tests.mjs';
-    refTests.withVirtualScroller(refTests.testFullScroll500px);
+    refTests.withVirtualScroller(refTests.testPart);
   </script>
 </html>

third_party/blink/web_tests/wpt_internal/virtual-scroller/resize-ref.html

@@ -3,6 +3,6 @@
   <style>body { overflow:hidden; }</style>
   <script type="module">
     import * as refTests from './resources/ref-tests.mjs';
-    refTests.withDiv(refTests.testFullScroll500px);
+    refTests.withDiv(refTests.testResize);
   </script>
 </html>

third_party/blink/web_tests/wpt_internal/virtual-scroller/resize.html

@@ -4,10 +4,10 @@
   <title>Creates more than a screenful of divs and then resizes the container.</title>
   <style>body { overflow:hidden; }</style>
   <link rel="author" title="Fergal Daly" href="mailto:fergal@chromium.org">
-  <link rel="match" href="full-scroll-500px-ref.html">
+  <link rel="match" href="resize-ref.html">
   <script type="module">
     import 'std:elements/virtual-scroller';
     import * as refTests from './resources/ref-tests.mjs';
-    refTests.withVirtualScroller(refTests.testFullScroll500px);
+    refTests.withVirtualScroller(refTests.testResize);
   </script>
 </html>

third_party/blink/web_tests/wpt_internal/virtual-scroller/resources/helpers.mjs

@@ -7,6 +7,8 @@
  * @package
  */
 
+const ONE_SECOND_MS = 1000;
+
 /**
  * Creates a DIV with id and textContent set to |id|.
  */
@@ -44,9 +46,14 @@ export function withElement(name, callback) {
 
 /**
  * Remove the reftest-wait class from the HTML element.
+ *
+ * This includes a hack to wait 1s to give the virtual-scroller
+ * elements time to settle.
 */
 export function stopWaiting() {
-  document.documentElement.classList.remove('reftest-wait');
+  setTimeout(() => {
+    document.documentElement.classList.remove('reftest-wait');
+  }, ONE_SECOND_MS);
 }
 
 /**