Incorrect error and crash for export as default

[JsonFreeman]

var x;
export { x as default };

This code should be legal, but I get "Identifier expected" on the default keyword. The grammar says that this can be an IdentifierName.

Also, this crashes the compiler:

                            if (specifier.name.text === "default") {
                                              ^
TypeError: Cannot read property 'text' of undefined
    at ts.forEach.exportDefault (built/local/tsc.js:22592:47)
    at Object.forEach (built/local/tsc.js:602:30)
    at _i (built/local/tsc.js:22591:28)
    at Object.forEach (built/local/tsc.js:602:30)
    at createExternalModuleInfo (built/local/tsc.js:22589:20)
    at emitAMDModule (built/local/tsc.js:22639:17)
    at emitSourceFileNode (built/local/tsc.js:22777:25)
    at emitJavaScriptWorker (built/local/tsc.js:22987:32)
    at emitNodeWithoutSourceMap (built/local/tsc.js:22804:17)
    at emitSourceFile (built/local/tsc.js:19555:17)

[ahejlsberg]

Both of these issues are fixed in a PR I'm working on.