LibJS: Convert some top-level tests to the new system

First test conversions! These look really good :)

Libraries/LibJS/Tests/switch-basic.js

@@ -1,14 +1,39 @@
-load("test-common.js");
+describe("basic switch tests", () => {
+    test("string case does not match number target", () => {
+        switch (1 + 2) {
+            case '3':
+                expect().fail();
+            case 3:
+                return;
+            case 5:
+            case 1:
+                break;
+            default:
+                break;
+        }
 
-switch (1 + 2) {
-case '3':
-    assertNotReached();
-case 3:
-    console.log("PASS");
-    break;
-case 5:
-case 1:
-    break;
-default:
-    break;
-}
+        expect().fail();
+    });
+
+    test("string concatenation in target", () => {
+        var a = "foo";
+        
+        switch (a + "bar") {
+        case 1:
+            expect().fail();
+        case "foobar":
+        case 2:
+            return;
+        }
+        expect().fail();
+    });
+
+    test("default", () => {
+        switch (100) {
+        default:
+            return;
+        }
+
+        expect().fail();
+    });
+});