Ship ES2015 sloppy-mode const semantics

test/mjsunit/global-const-var-conflicts.js

 // Copyright 2008 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.
 
 // Check that dynamically introducing conflicting consts/vars
 // is silently ignored (and does not lead to exceptions).
 
+// Flags: --legacy-const
+
 var caught = 0;
 
 eval("const a");
 try { eval("var a"); } catch (e) { caught++; assertTrue(e instanceof TypeError); }
 assertTrue(typeof a == 'undefined');
 try { eval("var a = 1"); } catch (e) { caught++; assertTrue(e instanceof TypeError); }
 assertTrue(typeof a == 'undefined');
 
 eval("const b = 0");
 try { eval("var b"); } catch (e) { caught++; assertTrue(e instanceof TypeError); }
@@ skipping 10 matching lines @@
 assertEquals(undefined, c);
 assertEquals(2, caught);
 
 eval("var d = 0");
 try { eval("const d"); } catch (e) { caught++; assertTrue(e instanceof TypeError); }
 assertEquals(0, d);
 assertEquals(3, caught);
 try { eval("const d = 1"); } catch (e) { caught++; assertTrue(e instanceof TypeError); }
 assertEquals(0, d);
 assertEquals(4, caught);