Allow 'transform' to be 'none' while animating.

This allows the computed value of 'transform' to be 'none' while the
transform property is animating, or while one of the independent
transform properties is set, or while offset-position or offset-path are
used.

This depends on the previous patch to avoid having the
transitions-specific bug fixed there cause new failures in
transform-interpolation-00{1,2,5,6}.html .

Fixed: 897358
Change-Id: I9ac00024a2497684e00a0407c59d357a5ab77e43
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3198752
Commit-Queue: David Baron <[email protected]>
Reviewed-by: Rune Lillesveen <[email protected]>
Cr-Commit-Position: refs/heads/main@{#927466}

animation-worklet/worklet-animation-local-time-null-1.https.html

@@ -47,7 +47,7 @@
   );
   animation.play();
   await waitForAsyncAnimationFrames(1);
-  assert_equals(getComputedStyle(target).transform, "matrix(1, 0, 0, 1, 0, 0)");
+  assert_equals(getComputedStyle(target).transform, "none");
 }, "A worklet which never sets localTime has no effect.");
 
 promise_test(async t => {
@@ -72,7 +72,7 @@
   );
   animation.play();
   await waitForAsyncAnimationFrames(1);
-  assert_equals(getComputedStyle(target).transform, "matrix(1, 0, 0, 1, 0, 0)");
+  assert_equals(getComputedStyle(target).transform, "none");
 }, "A worklet which sets localTime to null has no effect.");
 
 promise_test(async t => {
@@ -112,7 +112,7 @@
 
   await waitForAnimationFrameWithCondition(() => animation.currentTime > 1000);
   await waitForAsyncAnimationFrames(1);
-  assert_equals(getComputedStyle(target).transform, "matrix(1, 0, 0, 1, 0, 0)",
+  assert_equals(getComputedStyle(target).transform, "none",
       "The effect stops on nulling of localTime");
 
 }, "A worklet which changes localTime to from a number to null has no effect on transform.");