Augment set of WPT tests for interpolation of transform lists.

This patch improves test coverage for the interpolation of transform lists. Specifically, the new tests cover:
* mismatched list lengths with a partial prefix match
* mix of exact and primitive (e.g. scaleX & scaleY --> scale) matches

These new tests fail in Chrome without the patch (https://chromium-review.googlesource.com/c/chromium/src/+/1372025) to implement the algorithm outlined in transforms spec (https://drafts.csswg.org/css-transforms-1/#interpolation-of-transforms), but pass when tested in Firefox version 64.0.


Bug: 918643

Change-Id: I65bfe5b3c13c2fb33b3d2b926dc153135b140a63
Reviewed-on: https://chromium-review.googlesource.com/c/1393460Reviewed-by: Ian Vollick <vollick@chromium.org>
Commit-Queue: Kevin Ellis <kevers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#619635}

third_party/blink/web_tests/external/wpt/css/css-transforms/animation/list-interpolation-expected.txt

@@ -23,5 +23,15 @@ PASS Complete mismatch (except length): "scale(2) rotate(0deg) translate(100px)"
 PASS Complete mismatch (except length): Animation between "scale(2) rotate(0deg) translate(100px)" and "rotate(720deg) scale(2) translate(200px)" at progress 0.25
 PASS Complete mismatch including length: "scale(2) rotate(0deg)" and "rotate(720deg) scale(2) translate(200px)" are valid transform values
 PASS Complete mismatch including length: Animation between "scale(2) rotate(0deg)" and "rotate(720deg) scale(2) translate(200px)" at progress 0.25
+PASS Mismatched lengths (from is shorter), partial match: "rotate(0deg) scaleX(1)" and "rotate(720deg) translateX(0px) scaleX(2)" are valid transform values
+FAIL Mismatched lengths (from is shorter), partial match: Animation between "rotate(0deg) scaleX(1)" and "rotate(720deg) translateX(0px) scaleX(2)" at progress 0.25 assert_equals: expected "matrix(-1.25, 0, 0, -1, 0, 0)" but got "matrix(1.25, 0, 0, 1, 0, 0)"
+PASS Mismatched lengths (to is shorter), partial match: "rotate(720deg) translateX(0px) scaleX(2)" and "rotate(0deg) scaleX(1)" are valid transform values
+FAIL Mismatched lengths (to is shorter), partial match: Animation between "rotate(720deg) translateX(0px) scaleX(2)" and "rotate(0deg) scaleX(1)" at progress 0.25 assert_equals: expected "matrix(-1.75, 0, 0, -1, 0, 0)" but got "matrix(1.75, 0, 0, 1, 0, 0)"
+PASS Mismatched lengths (from is shorter), partial match on primitive: "scaleX(-3) scaleY(2)" and "scaleY(-3) translateX(0px) scaleX(2)" are valid transform values
+FAIL Mismatched lengths (from is shorter), partial match on primitive: Animation between "scaleX(-3) scaleY(2)" and "scaleY(-3) translateX(0px) scaleX(2)" at progress 0.25 assert_equals: expected "matrix(-2.5, 0, 0, 0, 0, 0)" but got "matrix(-1.75, 0, 0, 0.75, 0, 0)"
+PASS Mismatched lengths (to is shorter), partial match on primitive: "scaleY(-3) translateX(0px) scaleX(2)" and "scaleX(-3) scaleY(2)" are valid transform values
+FAIL Mismatched lengths (to is shorter), partial match on primitive: Animation between "scaleY(-3) translateX(0px) scaleX(2)" and "scaleX(-3) scaleY(2)" at progress 0.25 assert_equals: expected "matrix(0, 0, 0, -2.5, 0, 0)" but got "matrix(0.75, 0, 0, -1.75, 0, 0)"
+PASS Common prefix on primitive: "scaleY(-3) translateX(0px)" and "scaleX(-3) scaleY(2)" are valid transform values
+FAIL Common prefix on primitive: Animation between "scaleY(-3) translateX(0px)" and "scaleX(-3) scaleY(2)" at progress 0.25 assert_equals: expected "matrix(0, 0, 0, -2.5, 0, 0)" but got "matrix(0, 0, 0, -1.75, 0, 0)"
 Harness: the test ran to completion.
 

third_party/blink/web_tests/external/wpt/css/css-transforms/animation/list-interpolation.html

@@ -135,6 +135,56 @@ test_interpolation(
   [{ at: 0.25, expect: 'matrix(2, 0, 0, 2, 100, 0)' }],
   'Complete mismatch including length'
 );
+
+test_interpolation(
+  {
+    property: 'transform',
+    from: 'rotate(0deg) scaleX(1)',
+    to: 'rotate(720deg) translateX(0px) scaleX(2)'
+  },
+  [{at: 0.25, expect: 'rotate(180deg) matrix(1.25, 0, 0, 1, 0, 0)'}],
+  'Mismatched lengths (from is shorter), partial match'
+);
+
+test_interpolation(
+  {
+    property: 'transform',
+    from: 'rotate(720deg) translateX(0px) scaleX(2)',
+    to: 'rotate(0deg) scaleX(1)'
+  },
+  [{at: 0.25, expect: 'rotate(540deg) matrix(1.75, 0, 0, 1, 0, 0)'}],
+  'Mismatched lengths (to is shorter), partial match'
+);
+
+test_interpolation(
+  {
+    property: 'transform',
+    from: 'scaleX(-3) scaleY(2)',
+    to: 'scaleY(-3) translateX(0px) scaleX(2)'
+  },
+  [{at: 0.25, expect: 'scale(-2, 0) matrix(1.25, 0, 0, 1.75, 0, 0)'}],
+  'Mismatched lengths (from is shorter), partial match on primitive'
+);
+
+test_interpolation(
+  {
+    property: 'transform',
+    from: 'scaleY(-3) translateX(0px) scaleX(2)',
+    to: 'scaleX(-3) scaleY(2)'
+  },
+  [{at: 0.25, expect: 'scale(0, -2) matrix(1.75, 0, 0, 1.25, 0, 0)'}],
+  'Mismatched lengths (to is shorter), partial match on primitive'
+);
+
+test_interpolation(
+  {
+    property: 'transform',
+    from: 'scaleY(-3) translateX(0px)',
+    to: 'scaleX(-3) scaleY(2)'
+  },
+  [{at: 0.25, expect: 'scale(0, -2) matrix(1, 0, 0, 1.25, 0, 0)'}],
+  'Common prefix on primitive'
+);
 </script>
 </body>
 </html>