move all plugin tests out of babel-core and into their appropriate folders

packages/babel-plugin-transform-jscript/test/fixtures/jscript/simple-class/expected.js

@@ -0,0 +1,7 @@
+var Test = (function () {
+  function Test() {
+    babelHelpers.classCallCheck(this, Test);
+  }
+
+  return Test;
+})();