message: Make Info::init a constructor
  Summary: Code cleanup.
diff: @@ -87,8 +87,7 @@ impl HeapProfile {
  use summary::Info;
  let stacks = Stacks::collect(heap, None);
  - let mut info = Info { info: Vec::new() };
  - info.init(&stacks);
  + let mut info = Info::init(&stacks);
  // Add a totals column
  let total_id = stacks.totals_id;
  @@ -208,8 +207,10 @@ mod summary {
  &mut self.info[x.0]
  }
  - pub(crate) fn init(&mut self, stacks: &Stacks) {
  - self.init_children(&stacks.root, stacks.root_id);
  + pub(crate) fn init(stacks: &Stacks) -> Info {
  + let mut info = Info { info: Vec::new() };
  + info.init_children(&stacks.root, stacks.root_id);
  + info
  }
  fn init_children(&mut self, frame: &StackFrame, name: FunctionId) -> SmallDuration {
  @@ -320,8 +321,7 @@ _ignore = str([1]) # allocate a string in non_drop
  let stacks = Stacks::collect(eval.heap(), None);
  - let mut info = Info { info: Vec::new() };
  - info.init(&stacks);
  + let info = Info::init(&stacks);
  let total = FuncInfo::merge(info.info.iter());
  // from non-drop heap
  