Fix sloppy-mode 'const' under Harmony flag.

test/mjsunit/regress/regress-173361.js

Index: test/mjsunit/regress/regress-173361.js
diff --git a/test/mjsunit/regress/regress-2690.js b/test/mjsunit/regress/regress-173361.js
similarity index 95%
copy from test/mjsunit/regress/regress-2690.js
copy to test/mjsunit/regress/regress-173361.js
index 5fe7dc42dc693cf7f0a3e9a2b13c0f7b306189e2..f9cfb6684c0d52996c7ceac8412defbaf48a5eeb 100644
--- a/test/mjsunit/regress/regress-2690.js
+++ b/test/mjsunit/regress/regress-173361.js
@@ -25,5 +25,9 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-assertTrue(/\1[a]/.test("\1a"));
+// Flags: --harmony
 
+const x = 7;
+
+function f() { const y = 8; }
+f();