Port two webkit-xxx-interpolation.html to wpt/

These two tests already have corresponding tests in wpt, this CL just
adds some cases that are not yet covered under wpt. We still keep the
prefixed tests to ensure coverage.

Tested on both Chrome and Firefox, and they both pass the newly added
test cases.

Bug: 900581
Change-Id: Ic7ef80eb8d29179080d669b20279b59937c51960
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1805860Reviewed-by: Stephen McGruer <smcgruer@chromium.org>
Commit-Queue: Xida Chen <xidachen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#697227}

third_party/blink/web_tests/external/wpt/css/css-multicol/animation/column-count-interpolation.html

@@ -65,4 +65,16 @@ test_interpolation({
   {at: 1, expect: '1'},
   {at: 1.5, expect: '1'}
 ]);
+
+test_no_interpolation({
+  property: 'column-count',
+  from: 'initial',
+  to: '5',
+});
+
+test_no_interpolation({
+  property: 'column-count',
+  from: 'unset',
+  to: '5',
+});
 </script>

third_party/blink/web_tests/external/wpt/css/css-multicol/animation/column-rule-color-interpolation.html

@@ -74,4 +74,32 @@ test_interpolation({
   {at: 1, expect: 'rgb(170, 70, 70)'},
   {at: 1.5, expect: 'rgb(220, 20, 70)'},
 ]);
+
+test_interpolation({
+  property: 'column-rule-color',
+  from: 'unset',
+  to: 'rgb(0, 255, 0)',
+}, [
+  {at: -5, expect: 'rgb(255, 0, 255)'},
+  {at: -0.4, expect: 'rgb(98, 136, 98)'},
+  {at: 0, expect: 'rgb(70, 170, 70)'},
+  {at: 0.2, expect: 'rgb(56, 187, 56)'},
+  {at: 0.6, expect: 'rgb(28, 221, 28)'},
+  {at: 1, expect: 'rgb(0, 255, 0)'},
+  {at: 1.5, expect: 'rgb(0, 255, 0)'},
+]);
+
+test_interpolation({
+  property: 'column-rule-color',
+  from: 'orange',
+  to: 'blue'
+}, [
+  {at: -5, expect: '#ffff00'},
+  {at: -0.4, expect: '#ffe700'},
+  {at: 0, expect: 'orange'},
+  {at: 0.2, expect: '#cc8433'},
+  {at: 0.6, expect: '#664299'},
+  {at: 1, expect: 'blue'},
+  {at: 1.5, expect: 'blue'}
+]);
 </script>