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

Source/modules/serviceworkers/Request.cpp

Index: Source/modules/serviceworkers/Request.cpp
diff --git a/Source/modules/serviceworkers/Request.cpp b/Source/modules/serviceworkers/Request.cpp
index 228183ab44e1f76190ec19d5d79be7e9cc30d7fc..71744fbad68a3ff3b7138ff56ae12c08e44b03b6 100644
--- a/Source/modules/serviceworkers/Request.cpp
+++ b/Source/modules/serviceworkers/Request.cpp
@@ -194,12 +194,21 @@ Request* Request::create(ExecutionContext* context, Request* input, ExceptionSta
 
 Request* Request::create(ExecutionContext* context, Request* input, const Dictionary& init, ExceptionState& exceptionState)
 {
-    // "1. Let |request| be |input|'s associated request, if |input| is a
+    // "1. If input is a Request object, run these substeps:"
+    // "  1. If input's used flag is set, throw a TypeError."
+    // "  2. Set input's used flag."
+    if (input->bodyUsed()) {
+        exceptionState.throwTypeError(
+            "Cannot construct a Request with a Request object that has already been used.");
+        return 0;
+    }
+    input->setUsed();
+    // "2. Let |request| be |input|'s associated request, if |input| is a
     // Request object, and a new request otherwise."
-    // "2. Set |request| to a restricted copy of itself."
+    // "3. Set |request| to a restricted copy of itself."
     FetchRequestData* request(input->request()->createRestrictedCopy(context, SecurityOrigin::create(context->url())));
-    // "3. Let |fallbackMode| be null."
-    // "4. Let |fallbackCredentials| be null."
+    // "4. Let |fallbackMode| be null."
+    // "5. Let |fallbackCredentials| be null."
     // Instead of using null as a special fallback value, just pass the current
     // mode and credentials; it has the same effect.
     const FetchRequestData::Mode currentMode = request->mode();