JavaScript: fix CFG for EnhancedForStmt

javascript/ql/src/semmle/javascript/Stmt.qll

@@ -607,6 +607,10 @@ abstract class EnhancedForLoop extends LoopStmt {
   override Stmt getBody() {
     result = getChildStmt(2)
   }
+
+  override ControlFlowNode getFirstControlFlowNode() {
+    result = getIteratorExpr().getFirstControlFlowNode()
+  }
 }
 
 /** A `for`-`in` loop. */

javascript/ql/test/query-tests/Declarations/DeadStoreOfLocal/for-of-continue.js

@@ -0,0 +1,13 @@
+function f() {
+  let y = false;
+  for (const x of [1, 2, 3]) {
+    if (x > 0) {
+        y = true; // OK
+        continue;
+    }
+    return;
+  }
+  if (!y) {
+    console.log("Hello");
+  }
+}