Enable ts-helpers by default in generated projects

[bryanforbes]

All projects generated by angular-cli have a dependency on ts-helpers, but ts-helpers is not imported into the projects (or test harness) and the compiler outputs helpers in every file that needs them (which is every file that uses decorators or extends). Using ts-helpers in generated projects by default will have the benefit of reducing build sizes for the average user.

Generated projects should have the following modifications:

1. Add import 'ts-helpers'; at the top of src/main.ts and src/test.ts after import './polyfills.ts';
2. Add "noEmitHelpers": true to the compilerOptions object in src/tsconfig.json

Versions.

angular-cli: 1.0.0-beta.21
node: 6.9.1
os: darwin x64

Repro steps.

1. ng new test-project
2. grep for import 'ts-helpers'; and find 0 instances
3. Inspect src/tsconfig.js and find no "noEmitHelpers": true

[clydin]

I'm pretty sure that dependency is a leftover that was never removed.
And with the imminent release of TS 2.1, it will no longer be needed either way.

[nadavsinai]

although TS 2.1 has better support for external helpers some steps are still needed:

tsconfig.ts (aot too) --> add flag importHelpers:true
package.json --> add 'tslib' (official TS lib for helpers)

Typescript will insert the import statements itself
see here

this will give an important improvement in dist code size

[clydin]

Yes. However, this is blocked until the CLI supports 2.1.

[filipesilva]

I think the TS 2.1 approach is the more adequate one for this problem, yeah.

[sublimator]

When is angular-cli going to support TypeScript 2.1 ?

[filipesilva]

Superseded by #6277

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