Issue 1:
Issue originally made by James Whitney (whitneyit)

Bug information

Babel version: Babel 6.7.4

Node version: v5.4.0

npm version: v3.5.3

Input code

export default class A {
}

export default class B {
}

Description

I'm not sure if this is intended or has just been overlooked, but the above code does not produce an error.

I was able to find a few references to support this, namely a reference on [[ https://developer.mozilla.org/en/docs/web/javascript/reference/statements/export#Description | MDN]] and a post by Dr. Axel Rauschmayer's on [[ http://www.2ality.com/2014/09/es6-modules-final.html#an_overview_of_the_es6_module_syntax | 2ality ]], but I couldn't track it down specifically in the ES spec.

In addition, this is reported as an error on the [[ http://www.typescriptlang.org/Playground#src=export%20default%20class%20A%20%7B%0A%7D%0A%0Aexport%20default%20class%20B%20%7B%0A%7D| Typescript Playground]].

Issue 2:
Issue originally reported by @Edymov in babel/babel-preset-env#370

Hello! How use polifills for ES5 Arrays, IE 8, for example. I am using import babel-polyfill at the top of app.js, but array method does not pollified.

My configs are:

.babelrc

{
"presets": [
["env", {
"targets": {
"browsers": [
"> 1%",
"last 3 versions",
"ie 8"
]
},
"debug": true,
"useBuiltIns": true

}]
]
}

debug output

Using targets:
{
"chrome": "49",
"android": "4.4",
"edge": "13",
"firefox": "52",
"ie": "8",
"ios": "9.3",
"safari": "9.1"
}

Modules transform: commonjs

Using plugins:
check-es2015-constants {"android":"4.4","edge":"13","ie":"8","ios":"9.3","safari":"9.1"}
transform-es2015-arrow-functions {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
transform-es2015-block-scoped-functions {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
transform-es2015-block-scoping {"android":"4.4","edge":"13","ie":"8","ios":"9.3","safari":"9.1"}
transform-es2015-classes {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
transform-es2015-computed-properties {"android":"4.4","ie":"8"}
transform-es2015-destructuring {"chrome":"49","android":"4.4","edge":"13","firefox":"52","ie":"8","ios":"9.3","safari":"9.1"}
transform-es2015-duplicate-keys {"android":"4.4","ie":"8"}
transform-es2015-for-of {"chrome":"49","android":"4.4","edge":"13","firefox":"52","ie":"8","ios":"9.3","safari":"9.1"}
transform-es2015-function-name {"chrome":"49","android":"4.4","edge":"13","firefox":"52","ie":"8","ios":"9.3","safari":"9.1"}
transform-es2015-literals {"android":"4.4","firefox":"52","ie":"8"}
transform-es2015-object-super {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
transform-es2015-parameters {"android":"4.4","edge":"13","firefox":"52","ie":"8","ios":"9.3","safari":"9.1"}
transform-es2015-shorthand-properties {"android":"4.4","ie":"8"}
transform-es2015-spread {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
transform-es2015-sticky-regex {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
transform-es2015-template-literals {"android":"4.4","ie":"8"}
transform-es2015-typeof-symbol {"android":"4.4","ie":"8"}
transform-es2015-unicode-regex {"chrome":"49","android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
transform-regenerator {"chrome":"49","android":"4.4","firefox":"52","ie":"8","ios":"9.3","safari":"9.1"}
transform-exponentiation-operator {"chrome":"49","android":"4.4","edge":"13","ie":"8","ios":"9.3","safari":"9.1"}
transform-async-to-generator {"chrome":"49","android":"4.4","edge":"13","ie":"8","ios":"9.3","safari":"9.1"}
syntax-trailing-function-commas {"chrome":"49","android":"4.4","edge":"13","ie":"8","ios":"9.3","safari":"9.1"}

Using polyfills:
es6.typed.array-buffer {"chrome":"49","android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.typed.data-view {"ie":"8"}
es6.typed.int8-array {"chrome":"49","android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.typed.uint8-array {"chrome":"49","android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.typed.uint8-clamped-array {"chrome":"49","android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.typed.int16-array {"chrome":"49","android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.typed.uint16-array {"chrome":"49","android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.typed.int32-array {"chrome":"49","android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.typed.uint32-array {"chrome":"49","android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.typed.float32-array {"chrome":"49","android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.typed.float64-array {"chrome":"49","android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.map {"chrome":"49","android":"4.4","edge":"13","firefox":"52","ie":"8","ios":"9.3","safari":"9.1"}
es6.set {"chrome":"49","android":"4.4","edge":"13","firefox":"52","ie":"8","ios":"9.3","safari":"9.1"}
es6.weak-map {"chrome":"49","android":"4.4","edge":"13","firefox":"52","ie":"8"}
es6.weak-set {"chrome":"49","android":"4.4","edge":"13","firefox":"52","ie":"8"}
es6.reflect.apply {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.reflect.construct {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.reflect.define-property {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.reflect.delete-property {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.reflect.get {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.reflect.get-own-property-descriptor {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.reflect.get-prototype-of {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.reflect.has {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.reflect.is-extensible {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.reflect.own-keys {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.reflect.prevent-extensions {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.reflect.set {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.reflect.set-prototype-of {"android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.promise {"chrome":"49","android":"4.4","ie":"8","ios":"9.3","safari":"9.1"}
es6.symbol {"chrome":"49","android":"4.4","edge":"13","ie":"8","ios":"9.3","safari":"9.1"}
es6.object.assign {"android":"4.4","ie":"8"}
es6.object.is {"ie":"8"}
es6.object.set-prototype-of {"android":"4.4","ie":"8"}
es6.function.name {"chrome":"49","android":"4.4","edge":"13","firefox":"52","ie":"8","ios":"9.3","safari":"9.1"}
es6.string.raw {"android":"4.4","ie":"8"}
es6.string.from-code-point {"android":"4.4","ie":"8"}
es6.string.code-point-at {"android":"4.4","ie":"8"}
es6.string.repeat {"android":"4.4","ie":"8"}
es6.string.starts-with {"android":"4.4","ie":"8"}
es6.string.ends-with {"android":"4.4","ie":"8"}
es6.string.includes {"android":"4.4","ie":"8"}
es6.regexp.flags {"android":"4.4","edge":"13","ie":"8"}
es6.regexp.match {"chrome":"49","android":"4.4","edge":"13","ie":"8","ios":"9.3","safari":"9.1"}
es6.regexp.replace {"chrome":"49","android":"4.4","edge":"13","ie":"8","ios":"9.3","safari":"9.1"}
es6.regexp.split {"chrome":"49","android":"4.4","edge":"13","ie":"8","ios":"9.3","safari":"9.1"}
es6.regexp.search {"chrome":"49","android":"4.4","edge":"13","ie":"8","ios":"9.3","safari":"9.1"}
es6.array.from {"chrome":"49","android":"4.4","edge":"13","ie":"8","ios":"9.3","safari":"9.1"}
es6.array.of {"android":"4.4","ie":"8"}
es6.array.copy-within {"android":"4.4","ie":"8"}
es6.array.find {"android":"4.4","ie":"8"}
es6.array.find-index {"android":"4.4","ie":"8"}
es6.array.fill {"android":"4.4","ie":"8"}
es6.array.iterator {"android":"4.4","ie":"8"}
es6.number.is-finite {"ie":"8"}
es6.number.is-integer {"android":"4.4","ie":"8"}
es6.number.is-safe-integer {"android":"4.4","ie":"8"}
es6.number.is-nan {"ie":"8"}
es6.number.epsilon {"android":"4.4","ie":"8"}
es6.number.min-safe-integer {"android":"4.4","ie":"8"}
es6.number.max-safe-integer {"android":"4.4","ie":"8"}
es6.math.acosh {"android":"4.4","ie":"8"}
es6.math.asinh {"android":"4.4","ie":"8"}
es6.math.atanh {"android":"4.4","ie":"8"}
es6.math.cbrt {"android":"4.4","ie":"8"}
es6.math.clz32 {"android":"4.4","ie":"8"}
es6.math.cosh {"android":"4.4","ie":"8"}
es6.math.expm1 {"android":"4.4","ie":"8"}
es6.math.fround {"android":"4.4","ie":"8"}
es6.math.hypot {"android":"4.4","ie":"8"}
es6.math.imul {"android":"4.4","ie":"8"}
es6.math.log1p {"android":"4.4","ie":"8"}
es6.math.log10 {"android":"4.4","ie":"8"}
es6.math.log2 {"android":"4.4","ie":"8"}
es6.math.sign {"android":"4.4","ie":"8"}
es6.math.sinh {"android":"4.4","ie":"8"}
es6.math.tanh {"android":"4.4","ie":"8"}
es6.math.trunc {"android":"4.4","ie":"8"}
es7.array.includes {"android":"4.4","edge":"13","ie":"8","ios":"9.3","safari":"9.1"}
es7.object.values {"chrome":"49","android":"4.4","edge":"13","ie":"8","ios":"9.3","safari":"9.1"}
es7.object.entries {"chrome":"49","android":"4.4","edge":"13","ie":"8","ios":"9.3","safari":"9.1"}
es7.object.get-own-property-descriptors {"chrome":"49","android":"4.4","edge":"13","ie":"8","ios":"9.3","safari":"9.1"}
es7.string.pad-start {"chrome":"49","android":"4.4","edge":"13","ie":"8","ios":"9.3","safari":"9.1"}
es7.string.pad-end {"chrome":"49","android":"4.4","edge":"13","ie":"8","ios":"9.3","safari":"9.1"}
web.timers {"chrome":"49","android":"4.4","edge":"13","firefox":"52","ie":"8","ios":"9.3","safari":"9.1"}
web.immediate {"chrome":"49","android":"4.4","edge":"13","firefox":"52","ie":"8","ios":"9.3","safari":"9.1"}
web.dom.iterable {"chrome":"49","android":"4.4","edge":"13","firefox":"52","ie":"8","ios":"9.3","safari":"9.1"}