Introduce createRange(const EphemeralRange&)

Source/web/WebRange.cpp

Index: Source/web/WebRange.cpp
diff --git a/Source/web/WebRange.cpp b/Source/web/WebRange.cpp
index 1846be3ebd39ba3a2cbf8d278c6933176edb4cbd..dd9683906ebdc0a6dd2a289936cbf5e2b3ca1509 100644
--- a/Source/web/WebRange.cpp
+++ b/Source/web/WebRange.cpp
@@ -80,10 +80,7 @@ WebRange WebRange::fromDocumentRange(WebLocalFrame* frame, int start, int length
     LocalFrame* webFrame = toWebLocalFrameImpl(frame)->frame();
     Element* selectionRoot = webFrame->selection().rootEditableElement();
     ContainerNode* scope = selectionRoot ? selectionRoot : webFrame->document()->documentElement();
-    const EphemeralRange range = PlainTextRange(start, start + length).createRange(*scope);
-    if (range.isNull())
-        return WebRange();
-    return Range::create(range.document(), range.startPosition(), range.endPosition());
+    return createRange(PlainTextRange(start, start + length).createRange(*scope));
 }
 
 WebRange::WebRange(const PassRefPtrWillBeRawPtr<Range>& range)