Add WPT for rejecting CSSStyleValue with mismatched associated property

Add a new Web Platform Test verifying that StylePropertyMap.set() throws a
TypeError when a CSSStyleValue with an existing [[associatedProperty]] does
not match the property being assigned to.

Differential Revision: https://phabricator.services.mozilla.com/D271810

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1990419
gecko-commit: d8b8593f357774f2c99fbd835e1d47f306ebae63
gecko-reviewers: emilio

Author: janvarga

css/css-typed-om/the-stylepropertymap/declared/set.tentative.html

@@ -95,4 +95,15 @@
   assert_style_value_array_equals(result, [CSS.s(1), CSS.s(2)]);
 }, 'StylePropertyMap.set is case-insensitive');
 
+test(t => {
+  let styleMap = createDeclaredStyleMap(t, 'margin: 10px');
+
+  const result = styleMap.get('margin');
+  assert_equals(result.constructor.name, 'CSSStyleValue');
+
+  assert_throws_js(TypeError, () => {
+    styleMap.set('padding', result);
+  });
+}, 'Setting a property with a CSSStyleValue whose associated property does not match throws TypeError');
+
 </script>

css/css-typed-om/the-stylepropertymap/inline/set.tentative.html

@@ -95,4 +95,15 @@
   assert_style_value_array_equals(result, [CSS.s(1), CSS.s(2)]);
 }, 'StylePropertyMap.set is case-insensitive');
 
+test(t => {
+  let styleMap = createInlineStyleMap(t, 'margin: 10px');
+
+  const result = styleMap.get('margin');
+  assert_equals(result.constructor.name, 'CSSStyleValue');
+
+  assert_throws_js(TypeError, () => {
+    styleMap.set('padding', result);
+  });
+}, 'Setting a property with a CSSStyleValue whose associated property does not match throws TypeError');
+
 </script>