--- a/testing/web-platform/meta/MANIFEST.json
+++ b/testing/web-platform/meta/MANIFEST.json
@@ -203000,17 +203000,17 @@
    "14d79d1008193c96f0eadaf3e47ef321a429b905",
    "testharness"
   ],
   "service-workers/service-worker/update-after-oneday.https.html": [
    "7c8c6c3edca83d54f1838eccf3afb0b1223c7a44",
    "testharness"
   ],
   "service-workers/service-worker/update-bytecheck.https.html": [
-   "79b4a278f0e35646cfdffeebf8f0523e2772bc9b",
+   "6562348b198124822297c6b622c3e63870427672",
    "testharness"
   ],
   "service-workers/service-worker/update-recovery.https.html": [
    "aac5705d6844e4a33200418504adb57053a45be2",
    "testharness"
   ],
   "service-workers/service-worker/update.https.html": [
    "73c129838eda3c18365f384b8b0a5c32b5e9cf6d",
@@ -207644,21 +207644,21 @@
    "eee8ff07b3ec5e83e5f18305f5bc00eb72468443",
    "testharness"
   ],
   "web-animations/animation-model/animation-types/interpolation-per-property.html": [
    "55100f7d505bc8cbc966ced0d1337ed78534a553",
    "testharness"
   ],
   "web-animations/animation-model/animation-types/property-list.js": [
-   "4fa529fe470abb7a6fb4582d0174f1696b141f87",
+   "3d7b22ebf950652c8f806fff6aef68685a67ed5d",
    "support"
   ],
   "web-animations/animation-model/animation-types/property-types.js": [
-   "7b79c51f6dc5c33aae127406509770159815c290",
+   "38bdeff00d21201dc65c8e0fd8a337093ab807e5",
    "support"
   ],
   "web-animations/animation-model/animation-types/spacing-keyframes-filters.html": [
    "bd771a8a18245560221d92ea3495f81918c09848",
    "testharness"
   ],
   "web-animations/animation-model/animation-types/spacing-keyframes-shapes.html": [
    "03c3ab6815cfa96c07d5f95b6059fb276c50a25f",

new file mode 100644
--- /dev/null
+++ b/testing/web-platform/meta/web-animations/animation-model/animation-types/addition-per-property.html.ini
@@ -0,0 +1,6 @@
+prefs: [layout.css.contain.enabled:true, layout.css.initial-letter.enabled:true, layout.css.overflow-clip-box.enabled:true, layout.css.shape-outside.enabled:true]
+[addition-per-property.html]
+  type: testharness
+  [column-gap: "normal" onto "200px"]
+    expected: FAIL
+    bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1356241

--- a/testing/web-platform/meta/web-animations/animation-model/animation-types/interpolation-per-property.html.ini
+++ b/testing/web-platform/meta/web-animations/animation-model/animation-types/interpolation-per-property.html.ini
@@ -30,8 +30,19 @@ prefs: [layout.css.contain.enabled:true,
   [word-spacing supports animating as combination units "px" and "%"]
     expected: FAIL
     bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1291187
 
   [word-spacing supports animating as combination units "%" and "em"]
     expected: FAIL
     bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1291187
 
+  [column-gap uses discrete animation when animating between "normal" and "200px" with linear easing]
+    expected: FAIL
+    bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1356241
+
+  [column-gap uses discrete animation when animating between "normal" and "200px" with effect easing]
+    expected: FAIL
+    bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1356241
+
+  [column-gap uses discrete animation when animating between "normal" and "200px" with keyframe easing]
+    expected: FAIL
+    bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1356241

--- a/testing/web-platform/tests/web-animations/animation-model/animation-types/property-list.js
+++ b/testing/web-platform/tests/web-animations/animation-model/animation-types/property-list.js
@@ -359,22 +359,25 @@ var gCSSProperties = {
   'color-interpolation-filters': {
     // https://drafts.fxtf.org/filters-1/#propdef-color-interpolation-filters
     types: [
       { type: 'discrete', options: [ [ 'sRGB', 'linearRGB' ] ] }
     ]
   },
   'column-count': {
     // https://drafts.csswg.org/css-multicol/#propdef-column-count
-    types: [
+    types: [ 'positiveInteger',
+            { type: 'discrete', options: [ [ 'auto', '10' ] ] }
     ]
   },
   'column-gap': {
     // https://drafts.csswg.org/css-multicol/#propdef-column-gap
-    types: [ 'length' ]
+    types: [ 'length',
+	     {  type: 'discrete', options: [ [ 'normal', '200px' ] ] }
+    ]
   },
   'column-rule-color': {
     // https://drafts.csswg.org/css-multicol/#propdef-column-rule-color
     types: [ 'color' ]
   },
   'column-fill': {
     // https://drafts.csswg.org/css-multicol/#propdef-column-fill
     types: [
@@ -1513,17 +1516,16 @@ function propertyToIDL(property) {
   // https://w3c.github.io/web-animations/#animation-property-name-to-idl-attribute-name
   if (property === 'float') {
     return 'cssFloat';
   }
   return property.replace(/-[a-z]/gi,
                           function (str) {
                             return str.substr(1).toUpperCase(); });
 }
-
 function calcFromPercentage(idlName, percentageValue) {
   var examElem = document.createElement('div');
   document.body.appendChild(examElem);
   examElem.style[idlName] = percentageValue;
 
   var calcValue = getComputedStyle(examElem)[idlName];
   document.body.removeChild(examElem);
 

--- a/testing/web-platform/tests/web-animations/animation-model/animation-types/property-types.js
+++ b/testing/web-platform/tests/web-animations/animation-model/animation-types/property-types.js
@@ -174,16 +174,44 @@ const integerType = {
                                      { duration: 1000, composite: 'add' });
       testAnimationSamples(animation, idlName,
                            [{ time: 0,    expected: '-3' }]);
     }, property + ': integer');
   },
 
 };
 
+const positiveIntegerType = {
+  testInterpolation: function(property, setup) {
+    test(function(t) {
+      var idlName = propertyToIDL(property);
+      var target = createTestElement(t, setup);
+      var animation = target.animate({ [idlName]: [1, 3] },
+                                     { duration: 1000, fill: 'both' });
+      testAnimationSamples(animation, idlName,
+                           [{ time: 0,    expected: '1' },
+                            { time: 500,  expected: '2' },
+                            { time: 1000, expected: '3' }]);
+    }, property + ' supports animating as a positive integer');
+  },
+
+  testAddition: function(property, setup) {
+    test(function(t) {
+      var idlName = propertyToIDL(property);
+      var target = createTestElement(t, setup);
+      target.style[idlName] = 1;
+      var animation = target.animate({ [idlName]: [2, 5] },
+                                     { duration: 1000, composite: 'add' });
+      testAnimationSamples(animation, idlName,
+                           [{ time: 0,    expected: '3' }]);
+    }, property + ': positive integer');
+  },
+
+};
+
 const lengthPercentageOrCalcType = {
   testInterpolation: function(property, setup) {
     lengthType.testInterpolation(property, setup);
     percentageType.testInterpolation(property, setup);
 
     test(function(t) {
       var idlName = propertyToIDL(property);
       var target = createTestElement(t, setup);
@@ -1024,16 +1052,17 @@ const positionType = {
   },
 };
 
 const types = {
   color: colorType,
   discrete: discreteType,
   filterList: filterListType,
   integer: integerType,
+  positiveInteger: positiveIntegerType,
   length: lengthType,
   percentage: percentageType,
   lengthPercentageOrCalc: lengthPercentageOrCalcType,
   positiveNumber: positiveNumberType,
   transformList: transformListType,
   visibility: visibilityType,
   boxShadowList: boxShadowListType,
   textShadowList: textShadowListType,