Request construction spec changes to use the 'used' flag.

Source/modules/serviceworkers/Body.cpp

Index: Source/modules/serviceworkers/Body.cpp
diff --git a/Source/modules/serviceworkers/Body.cpp b/Source/modules/serviceworkers/Body.cpp
index cd4088d1de1a9be07a2afe53363835d8d833a604..c2fb2eee6aa436c305bc638a26cf4ac315c01144 100644
--- a/Source/modules/serviceworkers/Body.cpp
+++ b/Source/modules/serviceworkers/Body.cpp
@@ -97,6 +97,11 @@ bool Body::bodyUsed() const
     return m_bodyUsed;
 }
 
+void Body::setUsed()
+{
+    m_bodyUsed = true;
+}
+
 void Body::stop()
 {
     // Canceling the load will call didFail which will remove the resolver.