render() and renderSync() are deprecated for the sass package

[Rezyan]

Hi,

After having created a performance issue for the sass package, I learned that the render() and renderSync() methods were deprecated and suffered from performance issues:

• Sass compiles VERY slowly since v1.59 (8 times slower than v1.58) sass/dart-sass#1913 (comment)
• https://github.com/sass/dart-sass#legacy-javascript-api

We can also notice it in the comments of the code:

Ideally, we should suggest a way to use compile() and compileAsync() methods for the following lines:

gulp-sass/index.js

Line 145 in c04bb67

gulpSass.compiler.render(opts, (error, obj) => {

gulp-sass/index.js

Line 158 in c04bb67

filePush(file, gulpSass.compiler.renderSync(opts), callback);

Example from sass:

const sass = require('sass');

const result = sass.compile(scssFilename);

// OR

// Note that `compileAsync()` is substantially slower than `compile()`.
const result = await sass.compileAsync(scssFilename);

[nex3]

Heads up: we (the Sass team) are going to start emitting deprecation warnings for uses of the legacy API pretty soon.

[cbratschi]

Since Sass 1.79.1 the deprecation warnings are now active:

Deprecation Warning: The legacy JS API is deprecated and will be removed in Dart Sass 2.0.0.