turn internalRemap into a null inherited object, fixes a nasty bug where module import live bindings would return a function if they referenced a method on Object.prototype (eg. toString)

test/core/fixtures/transformation/misc/regression-lodash-tostring-import/actual.js

@@ -0,0 +1,2 @@
+import toString from "foo";
+toString;

test/core/fixtures/transformation/misc/regression-lodash-tostring-import/expected.js

@@ -0,0 +1,9 @@
+"use strict";
+
+var _interopRequire = function (obj) { return obj && obj.__esModule ? obj["default"] : obj; };
+
+var _toString = require("foo");
+
+var toString = _interopRequire(_toString);
+
+toString;