[WebSocket] Merge duplicated HTTP headers for devtools

Source/platform/network/WebSocketHandshakeRequest.cpp

Index: Source/platform/network/WebSocketHandshakeRequest.cpp
diff --git a/Source/platform/network/WebSocketHandshakeRequest.cpp b/Source/platform/network/WebSocketHandshakeRequest.cpp
index 1cc3f1473210654fed1406a97724fb62b3cb3777..902be3becf8329ae87d8168d2a2d535cfca05ef5 100644
--- a/Source/platform/network/WebSocketHandshakeRequest.cpp
+++ b/Source/platform/network/WebSocketHandshakeRequest.cpp
@@ -47,4 +47,13 @@ WebSocketHandshakeRequest::~WebSocketHandshakeRequest()
 {
 }
 
+void WebSocketHandshakeRequest::addAndMergeHeader(HTTPHeaderMap* map, const AtomicString& name, const AtomicString& value)
+{
+    HTTPHeaderMap::AddResult result = map->add(name, value);
+    if (!result.isNewEntry) {
+        // Inspector expects the "\n" separated format.
+        result.iterator->value = result.iterator->value + "\n" + String(value);
+    }
+}
+
 } // namespace WebCore