--- a/content/base/src/nsRange.cpp
+++ b/content/base/src/nsRange.cpp
@@ -57,16 +57,19 @@
 #include "nsIDOMNodeList.h"
 #include "nsGkAtoms.h"
 #include "nsContentUtils.h"
 #include "nsGenericDOMDataNode.h"
 #include "nsClientRect.h"
 #include "nsLayoutUtils.h"
 #include "nsTextFrame.h"
 #include "nsFontFaceList.h"
+#include "mozilla/Telemetry.h"
+
+using namespace mozilla;
 
 nsresult NS_NewContentIterator(nsIContentIterator** aInstancePtrResult);
 nsresult NS_NewContentSubtreeIterator(nsIContentIterator** aInstancePtrResult);
 
 /******************************************************
  * stack based utilty class for managing monitor
  ******************************************************/
 
@@ -238,16 +241,19 @@ nsRange::IsNodeSelected(nsINode* aNode, 
 /******************************************************
  * constructor/destructor
  ******************************************************/
 
 nsRange::~nsRange() 
 {
   NS_ASSERTION(!IsInSelection(), "deleting nsRange that is in use");
 
+  // Maybe we can remove Detach() -- bug 702948.
+  Telemetry::Accumulate(Telemetry::DOM_RANGE_DETACHED, mIsDetached);
+
   // we want the side effects (releases and list removals)
   DoSetRange(nsnull, 0, nsnull, 0, nsnull);
 } 
 
 /* static */
 nsresult
 nsRange::CreateRange(nsIDOMNode* aStartParent, PRInt32 aStartOffset,
                      nsIDOMNode* aEndParent, PRInt32 aEndOffset,

--- a/toolkit/components/telemetry/TelemetryHistograms.h
+++ b/toolkit/components/telemetry/TelemetryHistograms.h
@@ -396,16 +396,17 @@ HISTOGRAM(XUL_INITIAL_FRAME_CONSTRUCTION
 HISTOGRAM_BOOLEAN(XMLHTTPREQUEST_ASYNC_OR_SYNC, "Type of XMLHttpRequest, async or sync")
 HISTOGRAM_BOOLEAN(MULTIPART_XHR_RESPONSE, "XMLHttpRequest response was of type multipart/x-mixed-replace.")
 
 /**
  * DOM telemetry.
  */
 HISTOGRAM(DOM_TIMERS_FIRED_PER_NATIVE_TIMEOUT, 1, 3000, 10, EXPONENTIAL, "DOM: Timer handlers called per native timer expiration")
 HISTOGRAM(DOM_TIMERS_RECENTLY_SET, 1, 3000, 10, EXPONENTIAL, "DOM: setTimeout/setInterval calls recently (last 30s or more)")
+HISTOGRAM_BOOLEAN(DOM_RANGE_DETACHED, "DOM: Ranges that are detached on destruction (bug 702948)")
 
 /**
  * DOM Storage telemetry.
  */
 #define DOMSTORAGE_HISTOGRAM(PREFIX, TYPE, TYPESTRING, DESCRIPTION) \
   HISTOGRAM(PREFIX ## DOMSTORAGE_ ## TYPE ## _SIZE_BYTES, \
             1024, 32768, 10, EXPONENTIAL, "DOM storage: size of " TYPESTRING "s stored in " DESCRIPTION "Storage")
 #define DOMSTORAGE_KEY_VAL_SIZE(PREFIX, DESCRIPTION) \