Fix broken DataRef printer

https://chromium-review.googlesource.com/c/chromium/src/+/727781 broke printing of DataRefs
This commit makes DataRef print like this:

(gdb) p container_style.box_data_
$2 = DataRef(scoped_refptr((blink::ComputedStyleBase::StyleBoxData *)0x1e6143288
170))

Bug: 763844
Change-Id: I6ebcdd2d32b032659d3cc00973859c23ccb8b693
Reviewed-on: https://chromium-review.googlesource.com/826262Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Taiju Tsuiki <tzik@chromium.org>
Commit-Queue: Aleks Totic <atotic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524093}

third_party/WebKit/Tools/gdb/webkit.py

@@ -374,8 +374,7 @@ class BlinkDataRefPrinter:
         self.val = val
 
     def to_string(self):
-        return 'DataRef(%s)' % (
-            WTFRefOrOwnPtrPrinter(self.val['data_']).to_string())
+        return 'DataRef(%s)' % (str(self.val['data_']))
 
 
 def add_pretty_printers():