Use a helper function for React "inlining"

Either due to lower parsing costs or better type inference, this seems
to perform better than direct object inlining. (All along, the main win
was skipping a loop through props, not avoiding a function call.)

packages/babel-plugin-transform-react-inline-elements/test/fixtures/inline-elements/nested/expected.js

@@ -1,18 +1,4 @@
-({
-  $$typeof: babelHelpers.typeofReactElement,
-  type: "div",
-  key: null,
-  ref: null,
-  props: {
-    className: "foo",
-    children: [bar, {
-      $$typeof: babelHelpers.typeofReactElement,
-      type: Baz,
-      key: "baz",
-      ref: null,
-      props: Baz.defaultProps,
-      _owner: null
-    }]
-  },
-  _owner: null
-});
+babelHelpers.createRawReactElement("div", null, {
+  className: "foo",
+  children: [bar, babelHelpers.createRawReactElement(Baz, "baz", Baz.defaultProps)]
+});