Introduce extended mode.

test/mjsunit/harmony/block-scoping.js

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 10 matching lines @@
 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // Flags: --allow-natives-syntax --harmony-scoping
 // Test functionality of block scopes.
 
+// TODO(ES6): properly activate extended mode
+"use strict";
+
 // Hoisting of var declarations.
 function f1() {
   {
     var x = 1;
     var y;
   }
   assertEquals(1, x)
   assertEquals(undefined, y)
 }
 f1();
@@ skipping 212 matching lines @@
     const_accessors[i] = function() { return z; }
   }
   for (var j = 0; j < 10; j++) {
     y = j + 10;
     assertEquals(j, let_accessors[j]());
     assertEquals(y, var_accessors[j]());
     assertEquals(j, const_accessors[j]());
   }
 }
 f8();