Fix commitStyles for transforms.

Include layout object when retrieving values for computed properties.

Bug: 1056197
Change-Id: I8fd97b101047b473038a26dd9bb30dcff4ae6903
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2074801Reviewed-by: Robert Flack <flackr@chromium.org>
Commit-Queue: Kevin Ellis <kevers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#744688}

third_party/blink/renderer/core/animation/animation.cc

@@ -2129,7 +2129,7 @@ void Animation::commitStyles(ExceptionState& exception_state) {
   // 2. If, after applying any pending style changes, target is not being
   //    rendered, throw an "InvalidStateError" DOMException and abort these
   //    steps.
-  target->GetDocument().UpdateStyleAndLayoutTreeForNode(target);
+  target->GetDocument().UpdateStyleAndLayout(DocumentUpdateReason::kJavaScript);
   if (!target->GetLayoutObject()) {
     exception_state.ThrowDOMException(DOMExceptionCode::kInvalidStateError,
                                       "Target element is not rendered.");
@@ -2173,7 +2173,7 @@ void Animation::commitStyles(ExceptionState& exception_state) {
 
     CSSPropertyRef ref(property.GetCSSPropertyName(), target->GetDocument());
     const CSSValue* value = ref.GetProperty().CSSValueFromComputedStyle(
-       *style, nullptr, false);
+        *style, target->GetLayoutObject(), false);
     inline_style->setProperty(target->GetDocument().ToExecutionContext(),
                               property.GetCSSPropertyName().ToAtomicString(),
                               value->CssText(), "", ASSERT_NO_EXCEPTION);

third_party/blink/web_tests/external/wpt/web-animations/interfaces/Animation/commitStyles-expected.txt

@@ -7,6 +7,7 @@ PASS Commits values calculated mid-interval
 PASS Commits variable references as their computed values
 PASS Commits custom variables
 PASS Commits em units as pixel values
+PASS Commits transforms
 PASS Commits the intermediate value of an animation in the middle of stack
 PASS Commit composites on top of the underlying value
 PASS Triggers mutation observers when updating style

third_party/blink/web_tests/external/wpt/web-animations/interfaces/Animation/commitStyles.html

@@ -166,6 +166,18 @@ test(t => {
   assert_numeric_style_equals(getComputedStyle(div).width, 100);
 }, 'Commits em units as pixel values');
 
+test(t => {
+  const div = createDiv(t);
+  const animation = div.animate(
+    { transform: 'translate(20px, 20px)' },
+    { duration: 1, fill: 'forwards' }
+  );
+  animation.finish();
+  animation.commitStyles();
+  animation.cancel();
+  assert_equals(getComputedStyle(div).transform, 'matrix(1, 0, 0, 1, 20, 20)');
+}, 'Commits transforms');
+
 promise_test(async t => {
   const div = createDiv(t);
   div.style.opacity = '0.1';