LibJS: Demonstrate weird behaviour with 'break'

Author: https://github.com/alimpfard
Commit: https://github.com/SerenityOS/serenity/commit/8e89233bba3
Pull-request: https://github.com/SerenityOS/serenity/pull/3334
Reviewed-by: https://github.com/linusg ✅

Libraries/LibJS/Tests/loops/break-basic.js

@@ -0,0 +1,29 @@
+test("Toplevel break inside loop", () => {
+    var j = 0;
+    for (var i = 0; i < 9; ++i) {
+        break;
+        ++j;
+    }
+    expect(j).toBe(0);
+});
+
+test("break inside sub-blocks", () => {
+    var j = 0;
+    for (var i = 0; i < 9; ++i) {
+        if (j == 4)
+            break;
+        ++j;
+    }
+    expect(j).toBe(4);
+});
+
+test("break inside curly sub-blocks", () => {
+    var j = 0;
+    for (var i = 0; i < 9; ++i) {
+        if (j == 4) {
+            break;
+        }
+        ++j;
+    }
+    expect(j).toBe(4);
+});