Oilpan: Introduce TempRangeScope to avoid needless Range attaches on Document.

Source/core/editing/FrameSelection.cpp

Index: Source/core/editing/FrameSelection.cpp
diff --git a/Source/core/editing/FrameSelection.cpp b/Source/core/editing/FrameSelection.cpp
index 4315ab30238de60418445f05796eaf54c5012be0..881720bdc75c7e9438846cbf4103b473b8708106 100644
--- a/Source/core/editing/FrameSelection.cpp
+++ b/Source/core/editing/FrameSelection.cpp
@@ -329,6 +329,7 @@ void FrameSelection::nodeWillBeRemoved(Node& node)
 void FrameSelection::respondToNodeModification(Node& node, bool baseRemoved, bool extentRemoved, bool startRemoved, bool endRemoved)
 {
     ASSERT(node.document().isActive());
+    TemporaryRangeScope scope;

[yosin_UTC9, 2014/06/25 01:22:20]

It seems tempoary new Range object is created by |FrameSelection::firstRange()|
when |m_logicalRange| isn't null. But, cloned range is used for comparision. So,
we don't need to actually create new Range object.

We should change this logic to avoid creating Range object rather than using
|TemporaryRangeScope|.

[Mads Ager (chromium), 2014/06/25 11:41:42]

It seems that all the comparison logic is all hidden inside the Range object
abstraction at this point. It is not clear to me if there are other comparison
methods that give me what I need here or how to split out the comparison logic
from the Ranges. 

 
     bool clearRenderTreeSelection = false;
     bool clearDOMTreeSelection = false;