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

Source/core/html/HTMLTextFormControlElement.cpp

Index: Source/core/html/HTMLTextFormControlElement.cpp
diff --git a/Source/core/html/HTMLTextFormControlElement.cpp b/Source/core/html/HTMLTextFormControlElement.cpp
index 06a5579087d1bb2131efb3dd86802a41428cfacb..b9aa7e929b8cac2821c69278223ec4fcfec6497f 100644
--- a/Source/core/html/HTMLTextFormControlElement.cpp
+++ b/Source/core/html/HTMLTextFormControlElement.cpp
@@ -317,6 +317,7 @@ VisiblePosition HTMLTextFormControlElement::visiblePositionForIndex(int index) c
 {
     if (index <= 0)
         return VisiblePosition(firstPositionInNode(innerEditorElement()), DOWNSTREAM);
+    TemporaryRangeScope scope;
     RefPtrWillBeRawPtr<Range> range = Range::create(document());
     range->selectNodeContents(innerEditorElement(), ASSERT_NO_EXCEPTION);
     CharacterIterator it(range.get());
@@ -329,6 +330,7 @@ int HTMLTextFormControlElement::indexForVisiblePosition(const VisiblePosition& p
     Position indexPosition = pos.deepEquivalent().parentAnchoredEquivalent();
     if (enclosingTextFormControl(indexPosition) != this)
         return 0;
+    TemporaryRangeScope scope;
     ASSERT(indexPosition.document());
     RefPtrWillBeRawPtr<Range> range = Range::create(*indexPosition.document());
     range->setStart(innerEditorElement(), 0, ASSERT_NO_EXCEPTION);