message: refactor(compiler): allow parsing templates with custom leadingTriviaChars
  Move the definition leadingTriviaChars included in parsing a template
  to the parameters of parseTemplate. This allows overriding of the
  default leadingTriviaChars, which is needed by some pipelines like the
  indexing pipeline because leadingTriviaChars may throw off the recorded
  span of selectors.
  PR Close
diff: @@ -1940,6 +1940,12 @@ export interface ParseTemplateOptions {
  * but the new line should increment the current line for source mapping.
  */
  escapedString?: boolean;
  + /**
  + * An array of characters that should be considered as leading trivia.
  + * Leading trivia are characters that are not important to the developer, and so should not be
  + * included in source-map segments. A common example is whitespace.
  + */
  + leadingTriviaChars?: string[];
  }
  /**
  @@ -1957,7 +1963,7 @@ export function parseTemplate(
  const htmlParser = new HtmlParser();
  const parseResult = htmlParser.parse(
  template, templateUrl,
  - {...options, tokenizeExpansionForms: true, leadingTriviaChars: LEADING_TRIVIA_CHARS});
  + {leadingTriviaChars: LEADING_TRIVIA_CHARS, ...options, tokenizeExpansionForms: true});
  if (parseResult.errors && parseResult.errors.length > 0) {
  return {errors: parseResult.errors, nodes: [], styleUrls: [], styles: []};
  