LibJS: Fix switch skipping case evaluation when hitting the default case

When no case match we should not just execute the statements of the
default case but also of any cases below the default case.

Userland/Libraries/LibJS/Tests/switch-basic.js

@@ -67,11 +67,43 @@ describe("basic switch tests", () => {
         }
         expect(i).toBe(5);
     });
+
+    test("default branch is not taken if more exact branch exists", () => {
+        function switchTest(i) {
+            let result = 0;
+            switch (i) {
+                case 1:
+                    result += 1;
+                    break;
+                case 1:
+                    expect().fail();
+                case 2:
+                    result += 2;
+                default:
+                    result += 4;
+                case 3:
+                    result += 8;
+                    break;
+                case 2:
+                    expect().fail();
+            }
+            return result;
+        }
+
+        expect(switchTest(1)).toBe(1);
+        expect(switchTest(2)).toBe(14);
+        expect(switchTest(3)).toBe(8);
+        expect(switchTest(4)).toBe(12);
+    });
 });
 
 describe("errors", () => {
     test("syntax errors", () => {
         expect("switch () {}").not.toEval();
+        expect("switch () { case 1: continue; }").not.toEval();
+        expect("switch () { case 1: break doesnotexist; }").not.toEval();
+        expect("label: switch () { case 1: break not_the_right_label; }").not.toEval();
+        expect("label: switch () { case 1: continue label; }").not.toEval();
         expect("switch (foo) { bar }").not.toEval();
         expect("switch (foo) { default: default: }").not.toEval();
     });