designate all playground and es7 transformers as optional

src/babel/transformation/transformers/es7/abstract-references.js

@@ -4,6 +4,7 @@ import * as util from  "../../../util";
 import * as t from "../../../types";
 
 export var experimental = true;
+export var optional = true;
 
 var container = function (parent, call, ret, file) {
   if (t.isExpressionStatement(parent) && !file.isConsequenceExpressionStatement(parent)) {

src/babel/transformation/transformers/es7/comprehensions.js

@@ -4,6 +4,7 @@ import * as util from  "../../../util";
 import * as t from "../../../types";
 
 export var experimental = true;
+export var optional = true;
 
 export function ComprehensionExpression(node, parent, scope, file) {
   var callback = array;

src/babel/transformation/transformers/es7/exponentiation-operator.js

@@ -4,6 +4,7 @@ import build from "../../helpers/build-binary-assignment-operator-transformer";
 import * as t from "../../../types";
 
 export var experimental = true;
+export var optional = true;
 
 var MATH_POW = t.memberExpression(t.identifier("Math"), t.identifier("pow"));
 

src/babel/transformation/transformers/es7/object-rest-spread.js

@@ -3,6 +3,7 @@
 import * as t from "../../../types";
 
 export var experimental = true;
+export var optional = true;
 
 export function manipulateOptions(opts) {
   if (opts.whitelist.length) opts.whitelist.push("es6.destructuring");

src/babel/transformation/transformers/playground/mallet-operator.js

@@ -3,6 +3,7 @@ import build from "../../helpers/build-conditional-assignment-operator-transform
 import * as t from "../../../types";
 
 export var playground = true;
+export var optional = true;
 
 build(exports, {
   is(node, file) {

src/babel/transformation/transformers/playground/memoization-operator.js

@@ -2,6 +2,7 @@ import build from "../../helpers/build-conditional-assignment-operator-transform
 import * as t from "../../../types";
 
 export var playground = true;
+export var optional = true;
 
 build(exports, {
   is(node) {

src/babel/transformation/transformers/playground/method-binding.js

@@ -1,8 +1,11 @@
 import * as t from "../../../types";
 
 export var playground = true;
+export var optional = true;
 
 export function BindMemberExpression(node, parent, scope) {
+  console.error("Method binding is deprecated and will be removed in 5.0.0");
+
   var object = node.object;
   var prop   = node.property;
 
@@ -25,6 +28,8 @@ export function BindMemberExpression(node, parent, scope) {
 }
 
 export function BindFunctionExpression(node, parent, scope) {
+  console.error("Method binding is deprecated and will be removed in 5.0.0");
+
   var buildCall = function (args) {
     var param = scope.generateUidIdentifier("val");
     return t.functionExpression(null, [param], t.blockStatement([

src/babel/transformation/transformers/playground/object-getter-memoization.js

@@ -1,6 +1,7 @@
 import * as t from "../../../types";
 
 export var playground = true;
+export var optional = true;
 
 var visitor = {
   enter(node, parent, scope, state) {