message: refactor(compiler): remove unused `projection` const
  `projection` const is unused in `serializePlaceholderValue`.
  PR Close
diff: @@ -198,7 +198,6 @@ function findTemplateFn(ctx: number, templateIndex: number|null) {
  function serializePlaceholderValue(value: any): string {
  const element = (data: any, closed?: boolean) => wrapTag('#', data, closed);
  const template = (data: any, closed?: boolean) => wrapTag('*', data, closed);
  - const projection = (data: any, closed?: boolean) => wrapTag('!', data, closed);
  switch (value.type) {
  case TagType.ELEMENT:
  