Add a test for top-level let not creating a variable that'd show up in |with (global)| scope. No bug, r=jorendorff over IRC

--HG--
extra : rebase_source : 50e9ec9c7a97ec83f597fd07f3db57fc80c604c3

js/src/tests/browser.js

@@ -340,6 +340,10 @@ function jsTestDriverBrowserInit()
     {
       properties.version = '1.8';
     }
+    else if (properties.test.match(/^ecma_6\/LexicalEnvironment/))
+    {
+      properties.version = '1.8';
+    }
   }
 
   // default to language=type;text/javascript. required for

js/src/tests/ecma_6/LexicalEnvironment/shell.js

@@ -0,0 +1,5 @@
+// NOTE: This only turns on 1.8.5 in shell builds.  The browser requires the
+//       futzing in js/src/tests/browser.js (which only turns on 1.8, the most
+//       the browser supports).
+if (typeof version != 'undefined')
+  version(185);

js/src/tests/ecma_6/LexicalEnvironment/with-global-ignores-global-let-variables.js

@@ -0,0 +1,18 @@
+// |reftest| fails-if(Function("try{Function('let\x20x=5;');return(1,eval)('let\x20x=3;\\'x\\'\x20in\x20this');}catch(e){return(true);}")()) -- needs bug 589199 fix (top-level let not same as var)
+// Any copyright is dedicated to the Public Domain.
+// http://creativecommons.org/licenses/publicdomain/
+
+let v = "global-v";
+
+function f(v, global)
+{
+  with (global)
+    return v;
+}
+
+assertEq(f("argument-v", this), "argument-v");
+
+if (typeof reportCompare === "function")
+  reportCompare(true, true);
+
+print("Tests complete");