showcase: replace Highlight.js by the stark-pretty-print component in the ExampleViewer component

[christophercr]

I'm submitting a...

[ ] Regression (a behavior that used to work and stopped working in a new release)
[X] Bug report  
[ ] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead see https://github.com/NationalBankBelgium/stark/blob/master/CONTRIBUTING.md#got-a-question-or-problem

Current behavior

The ExampleViewer component uses the highlight.js library to leverage syntax highlighting. However, apart from the fact that there is another library we used to do this in the old Stark (PrismJS), the highlight.js library causes the following failure on the Travis build in Node 6:

ERROR in ./node_modules/highlight.js/lib/languages/sqf.js
Module build failed (from ./node_modules/@angular-devkit/build-optimizer/src/build-optimizer/webpack-loader.js):
RangeError: Maximum call stack size exceeded
    at Object.visitEachChild (/home/travis/build/NationalBankBelgium/stark/showcase/node_modules/@angular-devkit/build-optimizer/node_modules/typescript/lib/typescript.js:56952:28)
    at visitor (/home/travis/build/NationalBankBelgium/stark/showcase/node_modules/@angular-devkit/build-optimizer/src/transforms/wrap-enums.js:53:23)
    at visitNode (/home/travis/build/NationalBankBelgium/stark/showcase/node_modules/@angular-devkit/build-optimizer/node_modules/typescript/lib/typescript.js:56836:23)
    at Object.visitEachChild (/home/travis/build/NationalBankBelgium/stark/showcase/node_modules/@angular-devkit/build-optimizer/node_modules/typescript/lib/typescript.js:57078:46)
    at visitor (/home/travis/build/NationalBankBelgium/stark/showcase/node_modules/@angular-devkit/build-optimizer/src/transforms/wrap-enums.js:53:23)

This issue has been reported and it is open for some months already: highlightjs/highlight.js#1685

Expected behavior

• stark-pretty-print (ui: pretty-print - implement component/module #496) is used in the ExampleViewer component to provide syntax formatting and highlighting.
• Successful Travis builds in Node 6 and 8

Minimal reproduction of the problem with instructions

Trigger a production build for the showcase app with one of these commands under Node 6:

npm run build:showcase
npm run build:showcase:ghpages

What is the motivation / use case for changing the behavior?

PrismJS is better structured. It has meaningful classnames like: "token.block-comment", "token.boolean", "token.operator"... These make it easier to customize the css.

Environment

Angular version: 6.0.7

 
For Tooling issues:
- Node version: 6.X  
- Platform:  ALL