[BREAKING CHANGE] PopupToolGroup and friends: Pay off technical debt

PopupToolGroup.less
  Reimplemented the structure as a single table with three cells,
  rather than inline-block icon and inline-table with two cells.
  This fixes rendering glitches on IE11 (T74592, T74640) and
  incompatibility with ClippableElement (T78447).

Tool.js
  Changed DOM structure to support PopupToolGroup changes.
    Before:                          After:
      <a>                              <a>
        <span>Icon</span>                <span>Icon</span>
        <span>                           <span>Title</span>
          <span>Title</span>             <span>Accel</span>
          <span>Accel</span>           </a>
        </span>
      </a>

ListToolGroup.less
ListToolGroup.js
  Switched from display: inline-block to block, all it ever did was
  cause me headache.

Elsewhere
  Tweaks to match changes in Tool and PopupToolGroup.

Bug: T78499
Change-Id: Idc299e235b65317157e1022e3bebcc8cee8a2603
Merge "[BREAKING CHANGE] PopupToolGroup and friends: Pay off technical debt"