Fetch: Make Headers' constructor match the current spec IDL.

third_party/WebKit/Source/modules/fetch/Request.cpp

Index: third_party/WebKit/Source/modules/fetch/Request.cpp
diff --git a/third_party/WebKit/Source/modules/fetch/Request.cpp b/third_party/WebKit/Source/modules/fetch/Request.cpp
index c5619f07b39381fcf473d51bae4cc115c18954a9..9e9f6e2261ccb7cad34fb1e6b2279e9e34877bc7 100644
--- a/third_party/WebKit/Source/modules/fetch/Request.cpp
+++ b/third_party/WebKit/Source/modules/fetch/Request.cpp
@@ -305,7 +305,7 @@ Request* Request::createRequestWithRequestOrString(
   // We don't create a copy of r's Headers object when init's headers member
   // is present.
   Headers* headers = nullptr;
-  if (!init.headers && init.headersDictionary.isUndefinedOrNull()) {
+  if (!init.headers) {
     headers = r->getHeaders()->clone();
   }
   // "Empty |r|'s request's header list."
@@ -331,10 +331,7 @@ Request* Request::createRequestWithRequestOrString(
   }
   // "Fill |r|'s Headers object with |headers|. Rethrow any exceptions."
   if (init.headers) {
-    ASSERT(init.headersDictionary.isUndefinedOrNull());
     r->getHeaders()->fillWith(init.headers.get(), exceptionState);
-  } else if (!init.headersDictionary.isUndefinedOrNull()) {
-    r->getHeaders()->fillWith(init.headersDictionary, exceptionState);
   } else {
     ASSERT(headers);
     r->getHeaders()->fillWith(headers, exceptionState);