message: Use the faster `renderSync()` sass method
diff: @@ -22,10 +22,10 @@ import { Color as UtilColor } from '../render_process/gui/Util';
  // Dart Sass has the same API as Node Sass, but they don't publish typing files.
  // So we reuse the `node-sass` typing.
  import * as DartSass from 'sass';
  -import { Importer, ImporterReturnType, render } from 'node-sass';
  +import { Importer, ImporterReturnType, renderSync, SassError } from 'node-sass';
  const Sass = {
  - render: <typeof render>DartSass.render
  + renderSync: <typeof renderSync>DartSass.renderSync
  };
  const THEME_CONFIG = "theme.json";
  @@ -783,9 +783,9 @@ export class ThemeManager implements AcceptsConfigDatabase {
  if (DEBUG_SASS) {
  this._log.debug("Processing " + sassFileName);
  }
  - try {
  - const importer: Importer = (url: string, prev: string, done: (data: ImporterReturnType)=> void) => {
  + try {
  + const importer: Importer = (url: string, prev: string): ImporterReturnType => {
  const basePath = url;
  const contextBaseDir = path.dirname(prev);
  const dirName = path.join(contextBaseDir, path.dirname(basePath));
  @@ -818,15 +818,14 @@ export class ThemeManager implements AcceptsConfigDatabase {
  }
  try {
  const content = fs.readFileSync(candidateFileName, {encoding: 'utf-8'});
  - done( { contents: content } );
  + return { contents: content };
  } catch(err) {
  - done(err);
  + return err;
  }
  - return;
  }
  }
  - done(new Error("Unable to find " + basePath));
  + return new Error("Unable to find " + basePath);
  };
  // Start the compile using a small virtual 'boot' file.
  @@ -835,25 +834,24 @@ export class ThemeManager implements AcceptsConfigDatabase {
  this._log.debug("Root sass text: ", scssText);
  }
  - Sass.render({data: scssText, precision: 8, importer: importer }, (err, result) => {
  - if (err === null) {
  + try {
  + const result = Sass.renderSync({data: scssText, precision: 8, importer: importer });
  if (DEBUG_SASS) {
  this._log.debug("Succeeded done processing " + sassFileName);
  }
  resolve(result.css.toString('utf8'));
  - } else {
  + } catch(error) {
  + const err: SassError = error;
  this._log.warn("An SASS error occurred while processing " + sassFileName, err, err.message);
  if (DEBUG_SASS) {
  this._log.debug("Failed processing " + sassFileName);
  }
  cancel(new Error("An SASS error occurred while processing " + sassFileName + "\n" + err.message));
  }
  - });
  } catch (err) {
  this._log.warn("An error occurred while processing " + sassFileName, err);
  cancel(err);
  - return;
  }
  });
  }
  