W3C Test: Import web-platform-tests/html/semantics

LayoutTests/imported/web-platform-tests/html/semantics/forms/introduction-1/contains.json

+[
+    {
+        "id": "writing-a-form-s-user-interface",
+        "original_id": "writing-a-form's-user-interface"
+    },
+    {
+        "id": "implementing-the-server-side-processing-for-a-form",
+        "original_id": "implementing-the-server-side-processing-for-a-form"
+    },
+    {
+        "id": "configuring-a-form-to-communicate-with-a-server",
+        "original_id": "configuring-a-form-to-communicate-with-a-server"
+    },
+    {
+        "id": "client-side-form-validation",
+        "original_id": "client-side-form-validation"
+    },
+    {
+        "id": "enabling-client-side-automatic-filling-of-form-controls",
+        "original_id": "enabling-client-side-automatic-filling-of-form-controls"
+    },
+    {
+        "id": "improving-the-user-experience-on-mobile-devices",
+        "original_id": "improving-the-user-experience-on-mobile-devices"
+    },
+    {
+        "id": "the-difference-between-the-field-type-the-autofill-field-name-and-the-input-modality",
+        "original_id": "the-difference-between-the-field-type,-the-autofill-field-name,-and-the-input-modality"
+    },
+    {
+        "id": "input-author-notes",
+        "original_id": "input-author-notes"
+    }
+]