combine export declaration assignments into variable declarations

lib/6to5/modules/common.js

@@ -51,23 +51,32 @@ CommonJSFormatter.prototype.export = function (node, nodes) {
       VALUE: ref
     }, true));
   } else {
-    var id = declar.id;
+    var assign;
+
     if (t.isVariableDeclaration(declar)) {
-      id = declar.declarations[0].id;
+      var decl = declar.declarations[0]
+
+      if (decl.init) {
+        decl.init = util.template("exports-assign", {
+          VALUE: decl.init,
+          KEY:   decl.id
+        });
+      }
+
+      nodes.push(declar);
+    } else {
+      assign = util.template("exports-assign", {
+        VALUE: declar.id,
+        KEY:   declar.id
+      }, true);
+
+      nodes.push(declar);
+      nodes.push(assign);
+
+      if (t.isFunctionDeclaration(declar)) {
+        assign._blockHoist = true;
+      }
     }
-
-    var assign = util.template("exports-assign", {
-      VALUE: id,
-      KEY:   id
-    }, true);
-
-    nodes.push(declar);
-
-    if (t.isFunctionDeclaration(declar)) {
-      assign._blockHoist = true;
-    }
-
-    nodes.push(assign);
   }
 };