Implement bind:checked & bind:indeterminate on input[type=radio]

https://github.com/sveltejs/svelte/issues/1104
https://github.com/sveltejs/svelte/issues/1263

src/validate/html/validateElement.ts

@@ -111,9 +111,10 @@ export default function validateElement(
 					);
 				}
 
-				if (checkTypeAttribute(validator, node) !== 'checkbox') {
+				const checkTypeAttribute__ = checkTypeAttribute(validator, node);
+				if (checkTypeAttribute__ !== 'checkbox' && checkTypeAttribute__ !== 'radio') {
 					validator.error(
-						`'${name}' binding can only be used with <input type="checkbox">`,
+						`'${name}' binding can only be used with <input type="checkbox"> or <input type="radio">`,
 						attribute
 					);
 				}

test/runtime/samples/binding-input-radio-indeterminate/_config.js

@@ -0,0 +1,42 @@
+export default {
+	'skip-ssr': true,
+
+	data: {
+		indeterminate: true,
+	},
+
+	html: `
+		<input type="radio">
+		<p>checked? false</p>
+		<p>indeterminate? true</p>
+	`,
+
+	test(assert, component, target, window) {
+		const input = target.querySelector('input');
+		assert.equal(input.checked, false);
+		assert.equal(input.indeterminate, true);
+
+		const event = new window.Event('change');
+
+		input.checked = true;
+		input.indeterminate = false;
+		input.dispatchEvent(event);
+
+		assert.equal(component.get('indeterminate'), false);
+		assert.equal(component.get('checked'), true);
+		assert.htmlEqual(target.innerHTML, `
+			<input type="radio">
+			<p>checked? true</p>
+			<p>indeterminate? false</p>
+		`);
+
+		component.set({ indeterminate: true });
+		assert.equal(input.indeterminate, true);
+		assert.equal(input.checked, true);
+		assert.htmlEqual(target.innerHTML, `
+			<input type="radio">
+			<p>checked? true</p>
+			<p>indeterminate? true</p>
+		`);
+	},
+};

test/runtime/samples/binding-input-radio-indeterminate/main.html

@@ -0,0 +1,3 @@
+<input type='radio' bind:checked bind:indeterminate>
+<p>checked? {{checked}}</p>
+<p>indeterminate? {{indeterminate}}</p>

test/validator/samples/binding-input-checked/errors.json

@@ -1,5 +1,5 @@
 [{
-	"message": "'checked' binding can only be used with <input type=\"checkbox\">",
+	"message": "'checked' binding can only be used with <input type=\"checkbox\"> or <input type=\"radio\">",
 	"loc": {
 		"line": 1,
 		"column": 7