Fix non-Oilpan build following r372015.

TBR=oilpan-reviews,tkent
BUG=477839
NOTRY=true

Review URL: https://codereview.chromium.org/1640233005

Cr-Commit-Position: refs/heads/master@{#372091}

third_party/WebKit/Source/core/editing/FrameSelection.cpp

@@ -842,7 +842,7 @@ void FrameSelection::selectAll()
             selectStartTarget = document->body();
         }
     }
-    if (!root || editingIgnoresContent(root))
+    if (!root || editingIgnoresContent(root.get()))
         return;
 
     if (selectStartTarget && !selectStartTarget->dispatchEvent(Event::createCancelableBubble(EventTypeNames::selectstart)))