DevTools: allow builds with asserions when using DevTools front-end.

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

Index: third_party/WebKit/Source/core/editing/DOMSelection.cpp
diff --git a/third_party/WebKit/Source/core/editing/DOMSelection.cpp b/third_party/WebKit/Source/core/editing/DOMSelection.cpp
index 27cd215fe716607ca37b4b44533a735d84442dc5..54993df70d47a20209b689c88dbc2f1bcef7e877 100644
--- a/third_party/WebKit/Source/core/editing/DOMSelection.cpp
+++ b/third_party/WebKit/Source/core/editing/DOMSelection.cpp
@@ -383,9 +383,12 @@ RawPtr<Range> DOMSelection::getRangeAt(int index, ExceptionState& exceptionState
     if (!anchor.anchorNode()->isInShadowTree())
         return m_frame->selection().firstRange();
 
+    Node* node = shadowAdjustedNode(anchor);
+    if (!node) // crbug.com/595100

[yosin_UTC9, 2016/04/07 01:25:39]

Could you add a layout test for this case and for avoiding regression in future?
It seems we should change |shadowAdjustedNode()| not to return |nullptr|,
in theory, |shadowAdjustedNode()| should not be |nullptr|.

+        return nullptr;
     if (!visibleSelection().isBaseFirst())
-        return Range::create(*anchor.document(), focusNode(), focusOffset(), shadowAdjustedNode(anchor), anchorOffset());
-    return Range::create(*anchor.document(), shadowAdjustedNode(anchor), anchorOffset(), focusNode(), focusOffset());
+        return Range::create(*anchor.document(), focusNode(), focusOffset(), node, anchorOffset());
+    return Range::create(*anchor.document(), node, anchorOffset(), focusNode(), focusOffset());
 }
 
 void DOMSelection::removeAllRanges()