Upgrade selfhosted compilation to beta.2 (Take 2) (#6382)

* Avoid bug in current version of typeof-symbol transform.

* Selfhost Babel on most recent beta release.

.babelrc.js

@@ -1,5 +1,35 @@
 "use strict";
 
+// Blame Logan for this.
+// This works around https://github.com/istanbuljs/istanbuljs/issues/92 until
+// we have a version of Istanbul that actually works with 7.x.
+function istanbulHacks() {
+  return {
+    inherits: require("babel-plugin-istanbul").default,
+    visitor: {
+      Program: {
+        exit: function(path) {
+          if (!this.__dv__) return
+
+          const node = path.node.body[0];
+          if (
+            node.type !== "VariableDeclaration" ||
+            node.declarations[0].id.type !== "Identifier" ||
+            !node.declarations[0].id.name.match(/cov_/) ||
+            node._blockHoist !== 3
+          ) {
+            throw new Error("Something has gone wrong in Logan's hacks.");
+          }
+
+          // Gross hacks to put the code coverage block above all compiled
+          // import statement output.
+          node._blockHoist = 5;
+        },
+      },
+    },
+  };
+}
+
 let envOpts = {
   loose: true
 };
@@ -14,7 +44,7 @@ module.exports = {
   env: {
     cov: {
       auxiliaryCommentBefore: "istanbul ignore next",
-      plugins: ["istanbul"]
+      plugins: [istanbulHacks]
     }
   }
 };

package.json

@@ -11,14 +11,14 @@
   },
   "devDependencies": {
     "async": "^1.5.0",
-    "babel-cli": "7.0.0-alpha.18",
-    "babel-core": "7.0.0-alpha.18",
+    "babel-cli": "7.0.0-beta.2",
+    "babel-core": "7.0.0-beta.2",
     "babel-eslint": "8.0.0-alpha.15",
     "babel-plugin-istanbul": "^4.1.4",
-    "babel-preset-env": "2.0.0-alpha.18",
-    "babel-preset-flow": "7.0.0-alpha.18",
-    "babel-preset-stage-0": "7.0.0-alpha.18",
-    "babel-register": "7.0.0-alpha.18",
+    "babel-preset-env": "2.0.0-beta.2",
+    "babel-preset-flow": "7.0.0-beta.2",
+    "babel-preset-stage-0": "7.0.0-beta.2",
+    "babel-register": "7.0.0-beta.2",
     "babylon": "7.0.0-beta.27",
     "browserify": "^13.1.1",
     "bundle-collapser": "^1.2.1",

packages/babel-plugin-transform-react-constant-elements/src/index.js

@@ -1,4 +1,4 @@
-export default function({ types: t }) {
+export default function transformReactConstantElement({ types: t }) {
   const HOISTED = new WeakSet();
 
   const immutabilityVisitor = {