Add UseCounters for some nonstandard JavaScript features

test/mjsunit/regress/regress-4693.js

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// Flags: --harmony-sloppy-function
+// Flags: --harmony-sloppy-function --nolegacy-const
 
 // In sloppy mode we allow function redeclarations within blocks for webcompat.
 (function() {
   assertEquals(undefined, f);  // Annex B
   if (true) {
     assertEquals(2, f());
     function f() { return 1 }
     assertEquals(2, f());
     function f() { return 2 }
     assertEquals(2, f());
   }
   assertEquals(2, f());  // Annex B
 })();
 
 // Should still fail in strict mode
 assertThrows(`
   (function() {
     "use strict";
     if (true) {
       function f() { return 1 }
       function f() { return 2 }
     }
   })();
 `, SyntaxError);
+
+// Conflicts between let and function still throw
+assertThrows(`
+  (function() {
+    if (true) {
+      let f;
+      function f() { return 2 }
+    }
+  })();
+`, SyntaxError);
+
+assertThrows(`
+  (function() {
+    if (true) {
+      function f() { return 2 }
+      let f;
+    }
+  })();
+`, SyntaxError);
+
+// Conflicts between const and function still throw
+assertThrows(`
+  (function() {
+    if (true) {
+      const f;
+      function f() { return 2 }
+    }
+  })();
+`, SyntaxError);
+
+assertThrows(`
+  (function() {
+    if (true) {
+      function f() { return 2 }
+      const f;
+    }
+  })();
+`, SyntaxError);
+
+// Annex B redefinition semantics still apply with more blocks
+(function() {
+  assertEquals(undefined, f);  // Annex B
+  if (true) {
+    assertEquals(undefined, f);
+    { function f() { return 1 } }
+    assertEquals(1, f());
+    { function f() { return 2 } }
+    assertEquals(2, f());
+  }
+  assertEquals(2, f());  // Annex B
+})();