Revert "CrOS Shelf: Remove overflow shelf clip"

This reverts commit 0cee3055957800b3acd3f458c2972bcce8352db5.

Reason for revert: This change makes app icons bleed outside of the overflow when there are too many of them.

Original change's description:
> CrOS Shelf: Remove overflow shelf clip
> 
> Remove overflow shelf clip so that inkdrop ripples can propagate
> outside the overflow bubble.
> 
> The mask isn't really useful in the first place anyway.
> 
> See before/after screenshots here:
> 
>     https://bugs.chromium.org/p/chromium/issues/detail?id=631240#c14
> 
> Bug: 631240
> Change-Id: Iaa1d2f4e2e74bff34a708fa9e2cd7be5ed9a52fa
> Reviewed-on: https://chromium-review.googlesource.com/c/1429639
> Auto-Submit: Manu Cornet <manucornet@chromium.org>
> Commit-Queue: Xiyuan Xia <xiyuan@chromium.org>
> Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#625234}

TBR=xiyuan@chromium.org,manucornet@chromium.org

Change-Id: I51a004caf0a1b516fd21251621e9f716a241ca14
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 631240
Reviewed-on: https://chromium-review.googlesource.com/c/1432732
Reviewed-by: Manu Cornet <manucornet@chromium.org>
Commit-Queue: Manu Cornet <manucornet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#625407}
1 file changed