Bug 514025

**Description:**

I'd like a way to see what memory is *currently allocated* at a selected point in time, with stack traces and the ability to sort/filter.

**Current behaviour:**

The Consumed tab shows a stacked area graph of allocated memory over time. You can hover over segments to see what's allocated at that moment, and time filtering (v1.3.0+) shows new allocations within a range. The request is to show that data in a tree like the other views, e.g. `Bottom-Up`.

**Why this is insufficient:**

- **Hover tooltips are hard to read:** Allocation sources with similar sizes are visually indistinguishable, small allocations are invisible, and there's no way to sort or filter.
- **Time filtering shows the wrong thing:** It displays allocations *made during* a time range (delta), without a way to see what's *still held* at a point in time.

**Use case:**

When debugging memory usage, sometimes I want to know: "My app is idle; what's eating memory right now?" I can see the graph flat, but I can't easily find what constitutes that flat part of the graph.

**Possible implementations:**

This could be a new view, a column in existing views (Bottom-Up, Top-Down, etc.), or something else entirely; whatever fits best.