Remove unused UMAs about V8DOMWindowShell

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index c71b3fdfe55114a6f1c37c1bcdacc452c5760be7..b48cebd1a6d8d207fa80b6941cad5d21bd58e66b 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -35513,6 +35513,9 @@ Therefore, the affected-histogram name has to have at least one dot in it.
 
 <histogram name="WebCore.V8DOMWindowShell.createContext.IsolatedWorld"
     units="milliseconds">
+  <obsolete>
+    Deprecated 05/2013, we no longer have the code that uses this metric.
+  </obsolete>
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <summary>
     Duration of time taken to create a V8 Context for an isolated world.
@@ -35521,6 +35524,9 @@ Therefore, the affected-histogram name has to have at least one dot in it.
 
 <histogram name="WebCore.V8DOMWindowShell.createContext.MainWorld"
     units="milliseconds">
+  <obsolete>
+    Deprecated 05/2013, we no longer have the code that uses this metric.
+  </obsolete>
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <summary>
     Duration of time taken to create a V8 Context for the main world.