Bug 756918 - Fix aliased, empty destructuring let (r=waldo)

js/src/frontend/BytecodeEmitter.cpp

@@ -1033,6 +1033,7 @@ EmitEnterBlock(JSContext *cx, BytecodeEmitter *bce, ParseNode *pn, JSOp op)
         /* Beware the empty destructuring dummy. */
         if (!dn) {
             JS_ASSERT(i + 1 <= blockObj->slotCount());
+            blockObj->setAliased(i, bce->sc->bindingsAccessedDynamically());
             continue;
         }
 

js/src/jit-test/tests/basic/testBug756918.js

@@ -0,0 +1,6 @@
+// |jit-test| error:Error
+
+with({})
+  let([] = []) {
+    eval("throw new Error()");
+  }