feat(NodeXHRImpl): support file:// url fetching

[justindujardin]

• Please check if the PR fulfills these requirements
• The commit message follows our guidelines: https://github.com/angular/universal/blob/master/CONTRIBUTING.md#commit-message-format
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• What modules are related to this pull-request
• express-engine
• grunt-prerender
• gulp-prerender
• hapi-engine
• preboot
• universal-preview
• universal
• webpack-prerender
• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
  remove unused proxy imports from some test files

Allows the NodeXHRImpl to resolve file:// urls. Used in conjunction with a custom url resolver, this can be used to load templateUrl templates in a node environment.

• What is the current behavior? (You can also link to an open issue here)

Current:

/usr/local/bin/node /usr/local/lib/node_modules/gulp/bin/gulp.js --color --gulpfile /example/gulpfile.ts
[18:09:27] Requiring external module ts-node/register
[18:09:32] Using gulpfile /example/gulpfile.ts
[18:09:32] Starting 'prerender'...
ngOnInit Error: Failed to load src/app.html
Async Error: Failed to load src/app.html
ngOnStable Error: Failed to load src/app.html
preboot Error: Failed to load src/app.html
EXCEPTION: Failed to load src/app.html
Rendering Document Error: Failed to load src/app.html
Unhandled Promise rejection: Failed to load src/app.html ; Zone: <root> ; Task: Promise.then ; Value: Failed to load src/app.html
ngOnRendered Error: Failed to load src/app.html

With URL resolver to load templates from disk:

export class NodeUrlResolver extends UrlResolver {
  resolve(baseUrl: string, url: string): string {
    return `file://${path.resolve(path.join(ROOT, baseUrl, url))}`;
  }
}

/usr/local/bin/node /usr/local/lib/node_modules/gulp/bin/gulp.js --color --gulpfile /example/gulpfile.ts
[18:13:22] Requiring external module ts-node/register
[18:13:27] Using gulpfile /example/gulpfile.ts
[18:13:27] Starting 'prerender'...
EXCEPTION: Error during instantiation of Token Promise<ComponentRef>!.
ORIGINAL EXCEPTION: Error: Protocol "file:" not supported. Expected "http:".
ORIGINAL STACKTRACE:
Error: Protocol "file:" not supported. Expected "http:".
    at new ClientRequest (_http_client.js:53:11)
    at Object.exports.request (http.js:31:10)
    at Object.exports.get (http.js:35:21)
    at NodeXHRImpl.get (/example/node_modules/angular2-universal-preview/dist/node/platform/node_xhr_impl.js:29:14)
    at TemplateNormalizer.normalizeTemplate (angular2/src/compiler/template_normalizer.ts:42:24)
    at TemplateCompiler.normalizeDirectiveMetadata (angular2/src/compiler/template_compiler.ts:98:37)
    at angular2/src/compiler/template_compiler.ts:186:61
    at Array.map (native)
    at Object.Call (/example/node_modules/es6-shim/es6-shim.js:279:14)
    at Array.map (/example/node_modules/es6-shim/es6-shim.js:1275:17)

• What is the new behavior (if this is a feature change)?

With file protocol support in NodeXHRImpl:

/usr/local/bin/node /usr/local/lib/node_modules/gulp/bin/gulp.js --color --gulpfile /example/gulpfile.ts
[18:16:57] Requiring external module ts-node/register
[18:17:02] Using gulpfile /example/gulpfile.ts
[18:17:02] Starting 'prerender'...
EXCEPTION: Template parse errors:
Can't bind to 'href' since it isn't a known native property ("
        <span flex></span>
        <a md-peekaboo
           [ERROR ->][href]="https://github.com/justindujardin/ng2-material/releases/tag/v{{version}}"
           target=""): App@46:11

Which is another error in my project, but the template was properly loaded.

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)
  No
• Other information:

I'm not sure if this is a terrible idea or not. It seems to work well enough. What do you think?

[PatrickJS]

LGTM

[PatrickJS]

merged via e1a632c

[PatrickJS]

published as 0.86.0

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