[Drag and drop] problems when changing height after start

#### What is the expected behavior?
Drag and drop working :)

#### What is the current behavior?
If I change the height of elements (that are draggable) for example by hiding some elements **after I start dragging**, the drag and drop mechanism thinks the items are still the original height (and therefore rendering placeholder at wrong place and behaving incorrectly).

#### What are the steps to reproduce?
https://stackblitz.com/edit/angular-material2-issue-ggdtyr?file=app%2Fapp.component.css

(moving between columns does not work for some unknown reason but that is not important)

#### Which versions of Angular, Material, OS, TypeScript, browsers are affected?
newest ones

#### Is there anything else we should know?
If you point me in the right direction, I can provide a fix.

Start with the linked StackBlitz reproduction, especially app/app.component.css, and reproduce a height change after dragging begins. Trace the Angular drag-and-drop entry point to determine where the stale item dimensions affect placeholder placement. Done means the placeholder and drag behavior remain correct when draggable elements change height during a drag.

Written by the indexing model from the issue text.