Do not permit binding over catch parameters in for-of

test/mjsunit/es6/try-catch-for-of.js

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 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-if (this.Worker) {
-  var workerScript =
-    `var w = new Worker('postMessage(42)');
-     onmessage = function(parentMsg) {
-       w.postMessage(parentMsg);
-       var childMsg = w.getMessage();
-       postMessage(childMsg);
-     };`;
+// Test that we throw syntax errors when users attempt to shadow
+// try-catch bindings with for-of statements.
 
-  var w = new Worker(workerScript);
-  w.postMessage(9);
-  assertEquals(42, w.getMessage());
+function testEarlyError(s) {
+  assertThrows(function() {
+    eval("(function() { " + s + " })")
+  }, SyntaxError);
 }
+
+testEarlyError("try {} catch (e) { for (var e of []) {} }");
+
+assertThrows(function () {
+  try {
+    throw null;
+  } catch (e) {
+    eval("for (var e of []) {}");
+  }
+}, SyntaxError);
+
+// For-in statements should be fine, though.
+
+try {} catch (f) { for (var f in []) {} }
+try {
+  throw null;
+} catch (g) {
+  eval("for (var g in []) {}");
+}