Add errors for declarations which conflict with catch parameters.

test/mjsunit/es6/block-sloppy-function.js

 // Copyright 2015 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.
 
 // Test Annex B 3.3 semantics for functions declared in blocks in sloppy mode.
 // http://www.ecma-international.org/ecma-262/6.0/#sec-block-level-function-declarations-web-legacy-compatibility-semantics
 
 (function overridingLocalFunction() {
   var x = [];
   assertEquals('function', typeof f);
@@ skipping 173 matching lines @@
 })(1);
 
 assertThrows(function notInDefaultScope(x = y) {
   {
     function y() {}
   }
   assertEquals('function', typeof y);
   assertEquals(x, undefined);
 }, ReferenceError);
 
+// B.3.5 interacts with B.3.3 to allow this.
+(function hoistingThroughSimpleCatch() {
+  assertEquals(undefined, f);
+
+  try {
+    throw 0;
+  } catch(f) {
+    {
+      assertEquals(4, f());
+
+      function f() {
+        return 4;
+      }
+
+      assertEquals(4, f());
+    }
+  }
+
+  assertEquals(4, f());
+})();
+
+(function noHoistingThroughComplexCatch() {
+  try {
+    throw 0;
+  } catch({f}) {
+    {
+      assertEquals(4, f());
+
+      function f() {
+        return 4;
+      }
+
+      assertEquals(4, f());
+    }
+  }
+
+  assertThrows(()=>f, ReferenceError);
+})();
+
 // Test that hoisting from blocks does happen in global scope
 function globalHoisted() { return 0; }
 {
   function globalHoisted() { return 1; }
 }
 assertEquals(1, globalHoisted());
 
 // Also happens when not previously defined
 assertEquals(undefined, globalUndefinedHoisted);
 {
@@ skipping 85 matching lines @@
 throws = false;
 try {
   eval('{ function hoistWhenFrozen() {} }');
 } catch (e) {
   throws = true;
 }
 assertFalse(this.hasOwnProperty("hoistWhenFrozen"));
 assertThrows(() => hoistWhenFrozen, ReferenceError);
 // Should be assertFalse BUG(v8:4452)
 assertTrue(throws);