Revert "MacViews: exit early when trying to drag without a drag image instead...

Revert "MacViews: exit early when trying to drag without a drag image instead of crashing on Mojave"

This reverts commit 24c96bd0.

Reason for revert: Mac ASan 64 Tests failing views_unittests, test
case DragDropClientMacTest.ReleaseCapture,
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Mac%20ASan%2064%20Tests%20%281%29/43120

Original change's description:
> MacViews: exit early when trying to drag without a drag image instead of crashing on Mojave
> 
> This is a temporary patch to merge back to 69 while we figure out the root cause.
> 
> Bug: 876201
> Change-Id: Id87ac81f16b1cd3102c8605691421e8bc53dc401
> Reviewed-on: https://chromium-review.googlesource.com/1183991
> Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
> Commit-Queue: Leonard Grey <lgrey@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#585001}

TBR=ellyjones@chromium.org,lgrey@chromium.org

Change-Id: I80ec51eded1f8ba886eebc0c369ba23b96635c90
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 876201
Reviewed-on: https://chromium-review.googlesource.com/1185142Reviewed-by: Sky Malice <skym@chromium.org>
Commit-Queue: Sky Malice <skym@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585091}

ui/views/cocoa/drag_drop_client_mac.mm

@@ -104,12 +104,6 @@ void DragDropClientMac::StartDragAndDrop(
   NSImage* image = gfx::NSImageFromImageSkiaWithColorSpace(
       provider.GetDragImage(), base::mac::GetSRGBColorSpace());
 
-  // TODO(crbug/876201): This shouldn't happen. When a repro for this
-  // is identified and the bug is fixed, change the early return to
-  // a DCHECK.
-  if (!image || NSEqualSizes([image size], NSZeroSize))
-    return;
-
   base::scoped_nsobject<NSPasteboardItem> item([[NSPasteboardItem alloc] init]);
   [item setDataProvider:data_source_.get()
                forTypes:provider.GetAvailableTypes()];