[harmony] Move some regression tests to the right place

TBR=dslomov@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1027693003

Cr-Commit-Position: refs/heads/master@{#27339}

test/mjsunit/regress/regress-347906.js → test/mjsunit/es6/regress/regress-347906.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --allow-natives-syntax --harmony
+// Flags: --allow-natives-syntax
 
 function foo() {
   return Math.clz32(12.34);

test/mjsunit/regress/regress-411237.js → test/mjsunit/es6/regress/regress-411237.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --allow-natives-syntax --harmony
+// Flags: --allow-natives-syntax
 
 try {
   %OptimizeFunctionOnNextCall(print);