add readme entry for for-of assumeArray, use it (#6942)

packages/babel-plugin-transform-for-of/README.md

@@ -59,11 +59,12 @@ Without options:
 
 With options:
 
-```json
+```js
 {
   "plugins": [
     ["@babel/plugin-transform-for-of", {
-      "loose": true
+      "loose": true, // defaults to false
+      "assumeArray": true // defaults to false
     }]
   ]
 }
@@ -126,6 +127,13 @@ In loose mode an iterator's `return` method will not be called on abrupt complet
 Please see [google/traceur-compiler#1773](https://github.com/google/traceur-compiler/issues/1773) and
 [babel/babel#838](https://github.com/babel/babel/issues/838) for more information.
 
+### `assumeArray`
+`boolean`, defaults to `false`
+
+This will apply the optimization shown below to all for-of loops by assuming that _all_ loops are arrays.
+
+Can be useful when you just want a for-of loop to represent a basic for loop over an array.
+
 ### Optimization
 
 If a basic array is used, Babel will compile the for-of loop down to a regular for loop.

packages/babylon/package.json

@@ -24,7 +24,6 @@
   },
   "devDependencies": {
     "@babel/helper-fixtures": "7.0.0-beta.32",
-    "babel-plugin-transform-for-of-as-array": "1.0.4",
     "babel-plugin-transform-charcodes": "0.0.10",
     "charcodes": "0.0.10",
     "rollup": "^0.50.0",

packages/babylon/rollup.config.js

@@ -24,7 +24,10 @@ export default {
         ],
         "@babel/flow",
       ],
-      plugins: ["transform-charcodes", "transform-for-of-as-array"],
+      plugins: [
+        "transform-charcodes",
+        ["@babel/transform-for-of", { assumeArray: true }],
+      ],
     }),
     nodeResolve(),
   ],